Thermoplastic molding process and apparatus

ABSTRACT

A system and method for forming an article from thermoplastic material and fiber. The method includes heating thermoplastic material to form a molten thermoplastic material for blending with the fiber. The molten thermoplastic material is blended with the fibers to form a molten composite material having a concentration of fiber by weight. The molten composite material may then be extruded through dynamic dies to deliver discrete controlled material that is gravitated onto a lower portion of a mold. The lower portion of the mold may be moved in space and time while receiving the flow of composite material to deposit a predetermined quantity of molten composite material thereon conforming to mold cavities of the lower and an upper portion of the mold. The upper portion of the mold may be pressed against the predetermined quantity of molten composite material and closing on the lower portion of the mold to form the article.

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application is a continuation-in-part of U.S. patentapplication Ser. No. 10/293,005, filed Nov. 13, 2002, which is acontinuation-in-part of U.S. patent application Ser. No. 10/104,394,filed Mar. 25, 2002, pending, which is a divisional of U.S. applicationpatent Ser. No. 08/993,516, filed Dec. 18, 1997, now abandoned.

FIELD OF THE INVENTION

[0002] The present invention relates to a thermoplastic molding processand apparatus and especially to a thermoplastic process and apparatususing a proprietary dynamic gated die having adjustable gates forvarying the thickness of the extruded material, which material is moldedas it is passed from the extrusion die.

BACKGROUND OF THE INVENTION

[0003] Description of the Related Art

[0004] In the past it has been common to provide a wide variety ofmolding systems including the molding of a thermoplastic resin or athermoplastic composite part. In vacuum molding, a slab (constantthickness sheet) of heated thermoplastic material is placed on thevacuum mold and a vacuum drawn between the mold and the heated plasticmaterial to draw the plastic material onto the mold. Similarly, incompression molding, a lump or slab of preheated material is pressedbetween two molding forms which compress the material into a desiredpart or shape.

[0005] Related Patents

[0006] Prior U.S. patents which use thermoforming of material can beseen in the four Winstead patents, U.S. Pat. Nos. 4,420,300; 4,421,712;4,413,964; and 3,789,095. The Winstead '712 and '300 patents are for anapparatus for continuous thermoforming of sheet material including anextruder along with stretching means and a wheel having a female modethereon and a plurality of plug-assist means interlinked so as to forman orbiting device having a plug-assist member engaging the sheetmaterial about a substantial arc of wheel surface. The Winstead '964patent teaches an apparatus for continuously extruding and formingmolded products from a web of thermoplastic material while continuouslyseparating the product from the web, stacking and handling the products,and recycling the web selvage for further extrusion. The apparatus usesmultiple mode cavities in a rotating polygon configuration over aperipheral surface of which the biaxially oriented web is continuouslypositioned by a follower roller interfacing the polygon with a biaxialorientation device. The Winstead U.S. Pat. No. 3,789,095 is anintegrated method of continuously extruding low density formthermoplastic material and manufacturing three-dimensional formedarticles therefrom.

[0007] The Howell U.S. Pat. No. 3,868,209, is a twin sheet thermoformerfor fabricating a hollow plastic object from a pair of heat-fusiblethermoplastic sheets which are serially moved in a common horizontalplane from a heating station to a mold mechanism at a forming station.The Held, Jr. patent, U.S. Pat. No. 3,695,799, is an apparatus forvacuum forming hollow articles from two sheets of thermoplastic materialby passing the sheets of material through a heating zone while in aspaced relationship and between two mold halves. The mold halves arebrought together as a vacuum is pulled on each sheet to cause it toconform to the shape of its respective mold so as to mold a hollowarticle. The Budzynski et al., U.S. Pat. No. 5,551,860, is a blowmolding apparatus for making bottles which have rotating moldscontinuously rotating while aligning one mold at a time with anextrusion die handle for loading the mold. The Hujik patent, U.S. Pat.No. 3,915,608, is an injection molding machine for multi-layered shoesoles which includes a turntable for rotating a plurality of moldsthrough a plurality of work stations for continuously molding shoesoles. The Ludwig patent, U.S. Pat. No. 3, 302,243, is another apparatusfor injection molding of plastic shoes. The Lameris et al. patent, U.S.Pat. No. 3,224,043, teaches an injection molding machine having at leasttwo molds which can be rotated for alignment with plastic injectingnozzles. The Vismara patent, U.S. Pat. No. 4,698,001, is a machine formanufacturing molded plastic motorcycle helmets and which uses acompression type mold in which a pair of mold halves is shifted betweenpositions. The Krumm patent, U.S. Pat. No. 4,304,622, is an apparatusfor producing thick slabs of thermoplastic synthetic resins whichincludes a pair of extruders, each extruding a half slab strand to arespective roller assembly. The roller assemblies have final rollerswhich form a consolidation nip between them in which the two half slabsare bonded together.

[0008] Composites and Other Processes

[0009] Composites are materials formed from a mixture of two or morecomponents that produce a material with properties or characteristicsthat are superior to those of the individual materials. Most compositescomprise two parts, namely a matrix component and reinforcementcomponent(s). Matrix components are the materials that bind thecomposite together and they are usually less stiff than thereinforcement components. These materials are shaped under pressure atelevated temperatures. The matrix encapsulates the reinforcements inplace and distributes the load among the reinforcements. Sincereinforcements are usually stiffer than the matrix material, they arethe primary load-carrying component within the composite. Reinforcementsmay come in many different forms ranging from fibers, to fabrics, toparticles or rods imbedded into the matrix that form the composite.

[0010] Composite structures have existed for millions of years innature. Examination of the microstructure of wood or the bioceramics ofa seashell reveals the occurrence of composites found in nature andindicates that modem composite materials have essentially evolved tomimic structures found in nature. A perfect example of a compositematerial is concrete. Different forms of concrete offer an insight as tohow reinforcements work. The cement acts as the matrix, which holds theelements together, while the sand, gravel, and steel, act asreinforcements. Concrete made with only sand and cement is not nearly asstrong as concrete made from cement, sand, and stones, which, in turn,is not as strong as concrete reinforced with steel, sand and stones. Thematrix and reinforcement materials of concrete are blended, poured andmolded, typically in a form structure. In the generation of parts madewith other composite materials, the shape of a composite structure orpart is determined by the shape or geometry of the mold, die or othertooling used to form the composite structures.

[0011] There are many different types of composites, including plasticcomposites. Each plastic resin has its own unique properties, which whencombined with different reinforcements create composites with differentmechanical and physical properties. If one considered the number ofplastic polymers in existence today and multiplied that figure by thenumber of reinforcements available, the number of potential compositematerials is staggering. Plastic composites are classified within twoprimary categories: thermoset and thermoplastic composites.

[0012] In the case of thermoset composites, after application of heatand pressure, thermoset resins undergo a chemical change, whichcross-links the molecular structure of the material. Once cured, athermoset part cannot be remolded. Thermoset plastics resist highertemperatures and provide greater dimensional stability than mostthermoplastics because of the tightly cross-linked structure found inthermoset plastic. Thermoplastic matrix components are not asconstrained as thermoset materials and can be recycled and reshaped tocreate a new part.

[0013] Common matrix components for thermoplastic composites includepolypropylene (PP), polyethylene (PE), polyetheretherketone (PEEK) andnylon. Thermoplastics that are reinforced with high-strength,high-modulus fibers to form thermoplastic composites provide dramaticincreases in strength and stiffness, as well as toughness anddimensional stability.

[0014] Composite materials are used in numerous applications across abroad range of industries. Typically, composites are used to replaceproducts made of metal alloys or multi-component metal structuresassembled with fasteners or other connectors. Composites offersufficient strength, while providing a reduction in weight. This isparticularly important in industries such as automotive and aerospace,where the use of composite materials results in lighter, faster, morefuel-efficient and environmentally robust aircraft and automobiles.Composites may also be designed to replace wood, fiberglass and othermore traditional materials. The following is a partial list ofindustries that may have application for the use of large parts madefrom thermoplastic composite materials: aerospace, automotive,construction, home appliance, marine, material handling, medical,military, telecommunications, transportation and waste management.

[0015] In general, among other attributes, thermoplastic compositematerials are resistant to corrosion and offer long fatigue lives makingthem particularly attractive for many manufacturers. The fatigue liferefers to the period of time that a part lasts prior to exhibitingmaterial wear or significant stress, to the point of impairing theability of the part to perform to specification. Typically, compositesare utilized in applications where there is a desire to reduce theweight of a particular part while providing the strength and otherdesirable properties of the existing part. There are a number of partsmade from thermoset composite materials that are quite expensive. Thesetypes of parts are typically referred to as advanced composite materialsand are utilized most often in the military and aerospace industries.

[0016] Product development engineers and production engineers believethat thermoplastic composite materials will play an ever-increasing rolein modem technological development. New thermoplastic resins areregularly developed and more innovative methods of manufacturing arebeing introduced to lower the costs associated with manufacturing partsmade from composite materials. As the cost for manufacturing parts madewith thermoplastic composite materials reduces, the use of thermoplasticcomposites becomes a more viable solution for many commercial andindustrial applications.

[0017] Molding Methods Currently Available for Thermoplastic Composites

[0018] Most of the commercially available manufacturing technology forthermoplastic composites was adapted from methods for processingthermoset composites. Since these methods are designed for resin systemswith much lower viscosities and longer cure times, certaininefficiencies and difficulties have plagued the thermoplasticmanufacturing process. There are several methods of manufacturing withthermoplastic composites currently in use. Some of the most commonprocesses include compression molding, injection molding, and autoclaveprocessing, all of which can be used for the production of “near-netshape” parts, i.e., parts that substantially conform to the desired ordesigned shape after molding. Less common methods for processthermoplastic composites include pultrusion, vacuum forming, diaphragmforming and hot press techniques.

[0019] Compression Molding

[0020] Compression molding is by far the most widespread methodcurrently used for commercially manufacturing structural thermoplasticcomposite components. Typically, compression molding utilizes a glassmat thermoplastic (GMT) composite comprising polypropylene or a similarmatrix that is blended with continuous or chopped, randomly orientedglass fibers. GMT is produced by third-party material compounders, andsold as standard or custom size flat blanks to be molded. Using thispre-impregnated composite (or pre-preg as it is more commonly calledwhen using its thermoset equivalent), pieces of GMT are heated in anoven, and then laid on a molding tool. The two matched halves of themolding tool are closed under great pressure, forcing the resin andfibers to fill the entire mold cavity. Once the part is cooled, it isremoved from the mold with the assistance of an ejecting mechanism.

[0021] Generally, the matched molding tools used for GMT forming aremachined from high strength steel to endure the continuous applicationof the high molding pressure without degradation. These molds are oftenactively heated and cooled to accelerate cycle times and improve thesurface finish quality. GMT molding is considered one of the mostproductive composite manufacturing processes with cycle times rangingbetween 30 and 90 seconds. Compression molding does require a highcapital investment, however, to purchase high capacity presses(2000-3000 tons of pressure) and high pressure molds, therefore it isonly efficient for large production volumes. Lower volumes of smallerparts can be manufactured using aluminum molds on existing presses tosave some cost. Other disadvantages of the process are low fiberfractions (20% to 30%) due to viscosity problems, and the ability toonly obtain intermediate quality surface finishes.

[0022] Injection Molding

[0023] Injection molding is the most prevalent method of manufacturingfor non-reinforced thermoplastic parts, and is becoming more commonlyused for short-fiber reinforced thermoplastic composites. Using thismethod, thermoplastic pellets are impregnated with short fibers andextruded into a closed two-part hardened steel tool at injectionpressures usually ranging from 15,000 to 30,000 psi. Molds are heated toachieve high flow and then cooled instantly to minimize distortion.Using fluid dynamic analysis, molds can be designed which yield fiberswith specific orientations in various locations, but genericallyinjection molded parts are isotropic. The fibers in the final partstypically are no more than one-eighth (⅛)″ long, and the maximum fibervolume content is about 40%. A slight variation of this method is knownas resin transfer molding (RTM). RTM manufacturing utilizes mattedfibers that are placed in a mold which is then charged with resin underhigh pressure. This method has the advantages of being able to manuallyorient fibers and use longer fiber lengths.

[0024] Injection molding is the fastest of the thermoplastic processes,and thus is generally used for large volume applications such asautomotive and consumer goods. The cycle times range between 20 and 60seconds. Injection molding also produces highly repeatable near-netshaped parts. The ability to mold around inserts, holes and corematerial is another advantage. Finally, injection molding and RTMgenerally offer the best surface finish of any process.

[0025] The process discussed above suffers from real limitations withrespect to the size and weight of parts that can be produced byinjection molding, because of the size of the required molds andcapacity of injection molding machines. Therefore, this method has beenreserved for small to medium size production parts. Most problematicfrom a structural reinforcing point is the limitation regarding thelength of reinforcement fiber that can be used in the injection moldingprocess.

[0026] Autoclave Processing

[0027] Autoclave processing is yet another thermoplastic compositemanufacturing process used by the industry. Thermoplastic prepregs withunidirectional fibers or woven fabrics are laid over a single sidedtool. Several layers of bagging material are placed over the pre-pregassembly for surface finish, to prevent sticking, and to enable a vacuumto be drawn once it is placed in an autoclave. Inside the autoclave, thecomposite material is heated up and put under pressure to consolidateand cross-link the layers of material. Unlike compression and injectionmolding, the tool is an open mold and can be made of either aluminum orsteel since the pressures involved are much lower.

[0028] Because the autoclave process is much slower and more laborintensive, it is utilized primarily for very large, low volume partsthat require a high degree of accuracy; it is not conducive forproduction lines. Significant advantages of this method include highfiber volume fractions and control of the fiber orientation for enablingspecific material properties. This process is particularly useful forprototyping because the tooling is relatively inexpensive.

[0029] Molding Methods for Thermoplastic Composites Requiring “Long”Fibers

[0030] None of the processes described above are capable of producing athermoplastic composite reinforced with long fibers (i.e., greater thanabout one-half inch) that remain largely unbroken during the moldingprocess itself; this is especially true for the production of large andmore complex parts. Historically, a three-step process was utilized tomold such a part: (1) third party compounding of pre-preg compositeformulation; (2) preheating of pre-preg material in oven, and, (3)insertion of molten material in a mold to form a desired part. Thisprocess has several disadvantages that limit the industry's versatilityfor producing more complex, large parts with sufficient structuralreinforcement.

[0031] One disadvantage is that the sheet-molding process cannot producea part of varying thickness, or parts requiring “deep draw” ofthermoplastic composite material. The thicker the extruded sheet, themore difficult it is to re-melt the sheet uniformly through itsthickness to avoid problems associated with the structural formation ofthe final part. For example, a pallet having feet extrudingperpendicularly from the top surface is a deep draw portion of thepallet that cannot be molded using a thicker extruded sheet because theformation of the pallet feet requires a deep draw of material in the“vertical plane” and, as such, will not be uniform over the horizontalplane of the extruded sheet. Other disadvantages associated with thegeometric restrictions of an extruded sheet having a uniform thicknessare apparent and will be described in more detail below in conjunctionwith the description of the present invention.

[0032] The present invention is directed towards a molding system forproducing a thermoplastic resin of thermoplastic composite parts usingeither a vacuum or compression mold with parts being fed directly to themolds from an extrusion die while the thermoplastic slab still retainsthe heat used in heating the resins to a fluid state for forming thesheets of material through the extrusion die. The present inventionrelates to a thermoplastic molding process and apparatus and especiallyto a thermoplastic process and apparatus using a thermoplastic extrusiondie having adjustable gates for varying the thickness of the extrudedmaterial, which material is molded as it is passed from the extrusiondie.

[0033] The present invention is further directed towards a continualthermoforming system which is fed slabs of thermoplastic materialdirectly from an extruder forming the slabs of material onto a moldwhich can be rotated between stations. The thermoplastic material isextruded through an extrusion die which is adjustable for providingdeviations from a constant thickness plastic slab to a variablethickness across the surface of the plastic slab. The variable thicknesscan be adjusted for any particular molding run or can be continuouslyvaried as desired. This allows for continuous molding or thermoplasticmaterial having different thickness across the extruded slab and throughthe molded part to control the interim part thickness of the molded partso that the molded part can have thick or thin spots as desiredthroughout the molded part. The present invention is not limited as tosize, shape, composition, weight or strength of a desired partmanufactured by the extrusion molding process.

SUMMARY OF THE INVENTION

[0034] A thermoplastic molding system includes a thermoplastic extrusiondie for the extrusion of a thermoplastic slab profiled by adjustable diegate members, i.e., dynamic die settings, for varying the thickness ofthe extruded material in different parts of the extruded slab. Thethermoplastic extrusion die has a trimmer for cutting the extrudedthermoplastic slab from the thermoplastic extrusion die. A plurality ofthermoplastic molds, which may be either vacuum or compression molds,are each mounted on a movable platform, such as a rotating platform, formoving one mold at a time into a position to receive a thermoplasticslab being trimmed from the thermoplastic extrusion die. A molded partis formed with a variable thickness from a heated slab of thermoplasticmaterial being fed still heated from the extrusion die. A plurality ofmolds are mounted to a platform to feed one mold into a loading positionfor receiving a thermoplastic slab from the extrusion die and a secondmold into a release position for removing the formed part from the mold.The platform may be a shuttle or a rotating platform and allows eachmolded part to be cooled while another molded part is receiving athermoplastic slab. A thermoplastic molding process is provided havingthe steps of selecting a thermoplastic extrusion die setting inaccordance with the apparatus adjusting the thermoplastic extrusion diefor varying the thickness of the extruded material passing therethroughin different parts of the extruded slab. The thermoplastic material isheated to a fluid state and extruded through the selected thermoplasticdie which has been adjusted for varying the thickness of the extrudedmaterial in different parts of the extruded slab, trimming the extrudedthermoplastic slab having a variable thickness to a predetermined size,and directing each trim slab of heated thermoplastic material onto athermoforming mold, and molding a predetermined part in the mold so thatthe molded part is formed with a variable thickness from a slab ofmaterial heated during extrusion of the material.

[0035] “This extrusion-molding” process also facilitates the formationof thermoplastic composite structures reinforced with long fibers(greater than about one-half inch) because the extruder dispenses themolten, thermoplastic composite material through the dynamic die,gravitating the material directly onto a lower mold that is movable withrespect to the position of the dynamic die. As used herein, the term“lower mold” refers to the lower half of a matched-mold into whichthermoplastic material is directed. Similarly, the term “upper mold”refers to the upper half of the matched-mold within which the desiredthermoplastic part is formed, when the upper and lower mold halves arecombined i.e., closed. The lower mold may be moved via a trolley to fillthe cavity of the mold with varying quantities of the thermoplasticcomposite material. For example, if the cavity defined by the lower andan upper mold is larger over a certain horizontal range, the lower moldmay be slowed down to receive more molten thermoplastic compositematerial in that region. The dynamic die employs flow control elementsthat vary or regulate the flow of the molten extruded thermoplasticcomposite material to deliver different quantities of material from eachof the flow control element, to deposit the material selectively acrossthe width of the lower mold in a direction perpendicular to thedirection it is moving. The thermoplastic composite material may bemolded with long fibers (greater than about one-half inch) having aconcentration of at least ten percent (10%) by weight to as much asfifty to sixty percent (50-60%) by weight, with low fiber-fracturerates. After the molten extruded thermoplastic composite materialgravitates onto the lower mold, the trolley is automatically transportedinto a press that closes the upper mold onto the lower mold to form thecomposite part.

[0036] One embodiment according to the principles of the presentinvention includes a system and method for forming an article fromthermoplastic material and fiber. The method includes heatingthermoplastic material to form a molten thermoplastic material whileblending with the fiber. The molten thermoplastic material is blendedwith the fibers to form a molten composite material having a desiredconcentration of fiber by weight and/or volume. The molten compositematerial may then be extruded through the dynamic die to form aprescribed flow of composite material and gravitated onto a lowerportion of a mold for forming the article. The lower mold may bediscretely moved in space and time at varying speeds while receiving theflow of composite material to deposit a predetermined quantity of moltencomposite material thereon conforming exactly to the amount of materialrequired in the mold cavity of the lower mold. The upper portion of themold may be pressed against the predetermined quantity of moltencomposite material and closing on the lower portion of the mold to formthe article.

[0037] In another embodiment of the invention, a molded thermoplasticarticle is provided. The article comprises a fibrous material embeddedin a thermoplastic resin matrix, and is prepared by a low shear process.The lengths of the fibers before molding are about 0.5-3 inches long,and the lengths of the fibers in the molded article are greater thanabout 60% of their pre-molded lengths. The fibrous material comprises5-55% of the total weight of the compounded mixture. Less than about 20%of the fibers of the fibrous material in the molded thermoplasticarticle are oriented in the same direction, and the mechanicalproperties of the molded article in the x-, y-, and z-planes are within20% of each other. The mechanical properties of the article aresubstantially anisotropic.

[0038] In another aspect of the invention, a process for preparing amolded thermoplastic article is provided. The process for preparing themolded thermoplastic article generally comprises the steps of:

[0039] a) melt compounding a mixture of a thermoplastic resin, a fibrousmaterial, and any optional additives using a low shear single screw;

[0040] b) extruding the mixture through a sheet extrusion die using lowshear extrusion;

[0041] c) depositing the extruded mixture into a first half of ahorizontally-movable matched mold in approximately the general shape ofthe article; and

[0042] d) compression molding the deposited mixture with the second halfof the matched mold such that pressures in the range of 100-1,000 psiand substantially little movement of the molten mixture are required tocomplete consolidation and molding of the thermoplastic article.Accordingly, the invention can be distinguished over vacuum formingprocesses and sheet forming processes.

BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Other objects, features, and advantages of the present inventionwill be apparent from the written description and the drawings in which:

[0044]FIG. 1 is a top plan view of a molding system in accordance withthe present invention,

[0045]FIG. 2 is a side elevation view of the molding apparatus of FIG.1,

[0046]FIGS. 3A-3E are plan views of the mold of FIGS. 1 and 2 indifferent steps of the process of the present invention;

[0047]FIG. 4 is a side elevation of the extruder of FIGS. 1 and 2,

[0048]FIG. 5 is a rear elevation of the extruder of FIG. 4,

[0049]FIG. 6A is an exemplary schematic diagram of an extrusion-moldingsystem according to FIG. 1 operable to form structural parts;

[0050]FIG. 6B is another exemplary block diagram of theextrusion-molding system 600 a of FIG. 6A;

[0051]FIG. 7 is an exemplary exploded view of the dynamic die of FIG. 6Adepositing the extruded composite material on the lower mold assupported by the trolley;

[0052]FIG. 8A is an exemplary flow diagram describing theextrusion-molding process that may be utilized to form articles orstructural parts by using either two- or three-axis control fordepositing the composite material onto the lower mold of FIG. 6A,

[0053]FIG. 8B is an another exemplary flow diagram for producingstructural parts utilizing the extrusion-molding system of FIG. 6A viathe three-axis control extrusion-molding process;

[0054]FIG. 9 is an exemplary block diagram of a controller of FIG. 6Ainterfacing with controllers operating in components of theextrusion-molding system of FIG. 6A;

[0055]FIG. 10 is a more detailed exemplary block diagram of thecontroller of FIG. 6A;

[0056]FIG. 11 is an exemplary block diagram of the software that isexecuted by a processor operating the controller of FIG. 10;

[0057]FIG. 12 is an exemplary schematic of the flow control elements anda lower mold, which is sectioned into a grid, to deposit extrudedcomposite material in accordance with the extrusion-molding system ofFIG. 6A;

[0058]FIG. 13 is a top view of the flow control elements as aligned todeposit the composite material onto the lower mold of FIG. 6A;

[0059]FIG. 14 is an exemplary perspective top view of a corner of apallet produced by the extrusion-molding system of FIG. 6A;

[0060]FIGS. 15A and 15B are an exemplary perspective bottom and topviews, respectively, of a platform having hidden ribs formed by theextrusion-molding system of FIG. 6A;

[0061]FIGS. 16A and 16B are an exemplary structural parts having insertsformed by the extrusion-molding system of FIG. 6A, and

[0062]FIG. 17 is an exemplary flow diagram describing the operations forembedding an insert, such as a fastener, support, or other element, intoa structural part, such as those shown in FIGS. 16A and 16B, utilizingthe extrusion-molding system of FIG. 6A.

DETAILED DESCRIPTION OF THE INVENTION

[0063] For many years, a gap has existed in the composites manufacturingindustry that failed to provide a process to mass produce largethermoplastic composite structures or parts at the rates and laborefficiencies of compression or injection molding, with the accuracy andlow pressures of autoclave molding. The principles of the presentinvention provide for processes that closes this gap and produces suchthermoplastic composite parts. The processes are suitable for mid tohigh production volumes of parts, and may produce large parts andstructures with high reinforcing fiber concentration and at low moldingpressures.

[0064] Referring to FIGS. 1 and 2 of the drawings, a thermoformingapparatus 10 for thermoforming parts from a thermoplastic resin or froma thermoplastic composite is illustrated having an extruder 11, a moldexchange station 12, and a compression mold station 13. The extruder hasa hopper 14 mounted on top for feeding a thermoplastic resin orcomposite material into an auger 15 where heaters are heating thethermoplastic material to a fluid material while the auger is feeding italong the length of the extruder path to an extrusion die 16 at the endthereof. The material being fed through the extruder and out theextrusion die is cut with a trimmer 17 mounted at the end of the die 16.The material is extruded in a generally flat plate slab (not shown) andis trimmed at predetermined points by the trimmer 17 as it leaves theextrusion die 16. A support platform 18 will support a traveling moldhalf 19 directly under the extrusion die 16 for receiving a slab ofthermoplastic material. The traveling mold half 19 has wheels 20 whichallow the mold half 19 to be moved from the platform 18 onto a rotatingplatform 21 (shown as mold half 19′) which is mounted on a centralrotating shaft 22 for rotation as indicated by the bi-directional arrow21′ in FIG. 1. The rotating platform 21 will have a second mold half 23thereon which can be fed into the compression molding station 13 (shownas mold half 23′) while the mold half 19 is on the platform 18. The moldhalf 23′ can be supported on a stationary platform 24 in the compressionstation directly beneath a common posing fixed mold half 25 mounted to amoving platen 26 where the molding operation takes place. Thus, the moldhalves 19 and 23 can shuttle back and forth so that one mold can becapturing a thermoplastic slab while the other mold half is molding apart. Each of the traveling mold halves 19, 23 has an electric motor 27for driving the mold half from the rotating platform 21 onto theplatform 18 or onto the stationary platform 24. A linear transducer 28can be mounted on the platform 18 for controlling the traveling moldhalves speed.

[0065] It should be noted at this point that the extruder 11 producesthe heated extruded slab still containing the heat energy onto thetraveling mold half where it is delivered to the compression mold 13 andmolded into a part without having to reheat a sheet of thermoplasticmaterial. As will also be noted hereinafter in connection with FIGS. 4and 5, the thermoplastic slab can also be of variable thicknessthroughout its width to enhance the thermoformed part made from themold.

[0066] Turning to FIGS. 3A-3E, the thermoplastic molding apparatus 10 isillustrated having the mold halves 19, 19′ and 23, 23′ in a series ofpositions in the operation of the press in accordance with the presentinvention. Each figure has the extruder 11 having the hopper 14 feedingthe thermoplastic resin or composite material into an auger 16 where itis heated before being extruded. In FIG. 3A, mold half 23′ is empty andmold half 19 is being charged with a hot melt directly from the extruder11. In FIG. 3B, the mold carrier moves the mold halves 19 and 23′ on therotating turntable 21. In FIG. 3C, the rotating turntable 21 rotates onthe central axis shaft 22 (not shown) between stations for loading aslab onto one mold half 23 and a loaded mold half 19′ into thecompression or vacuum molding machine 13. In FIG. 3D, the mold half 19′travels into the press 13 while the empty mold half 23 travels under theextrusion die 16 for loading with a slab of thermoplastic material. InFIG. 3E, the mold half 19′ is press cooled and the part is ejected whilemold half 23 is charged with a hot melt as it is moved by its carrierbelow the extrusion die 16 until completely charged.

[0067] Turning to FIGS. 4 and 5, the extrusion die 30 is illustratedhaving the die body 31 having the channel 32 for the feeding of a fluidthermoplastic material with the auger 15 of FIGS. 1 and 2 therethroughout the extrusion channel 33 to produce a sheet or slab of thermoplasticextruded material from the mouth 34. The die 30 has a plurality of gatedplates 35 each connected to a threaded shaft 36 driven by a gateactuator motor 37 which can be a hydraulic or pneumatic motor but, asillustrated, is an electrical stepper motor having a control line 38feeding to a remote controller 40 which can step the motor 37 in stepsto move the plate 35 in and out to vary the thickness of thethermoplastic slab passing the channel portion 41. A plurality of anynumber of motors 37 can be seen in FIG. 5 driving a plurality of plates,each mounted abutting the next plate, and each plate controlledseparately to thereby vary the plates 35 in the channel 41 in a widevariety of patters for producing a slab out the output portion 34 havingthickness which can vary across the width of the extruded slab. It willalso be clear that the gates 35 can be manually controlled byindividually threading each gate into and out to adjust the thickness ofany portion of the extrusion die and can, alternatively, be controlledby a controller 40 which can be a computer program to vary the thicknessof any portion of the extruded slab under remote control as desired.

[0068] A thermoplastic molding process is provided which includesselecting a thermoplastic extrusion die 16 or 30 for the extrusion of athermoplastic slab, which extrusion die has an adjustable die gatemembers for varying the thickness of the extruded material in differentparts of the extruded slab. The process includes adjusting thethermoplastic extrusion die for various thickness of the extrudedmaterial passing therethrough in different parts of the extruded slaband then heating a thermoplastic material to a fluid and extruding aslab of fluid thermoplastic material through the selected and adjustedthermoplastic extrusion die. The thermoplastic slab is then trimmed anddirected onto a heated thermoplastic material into a thermoforming mold19 or 23 and molded in a molding apparatus 13 to form a part with avariable thickness in the part.

[0069] It should be clear at this time that a thermoplastic moldingprocess and apparatus have been provided which allow for thethermoforming of a part with a variable thickness with an extrusion diewhich can be continuously controlled to vary the thickness of differentparts of the extruded slab being molded and that the molding isaccomplished while the thermoplastic slab is still heated to utilize theheat energy from the extrusion process. However, it should also be clearthat the present invention is not to be considered limited to the formsshown which are to be considered illustrative rather than restrictive.For example, although the extruded material is described sometimes as agenerally flat plate slab, it is also described as follows: (i)containing heat energy when delivered to the compression mold 13 toobviate rehashing, (ii) having a variable thickness throughout itswidth, (iii) being a hot melt when charged into the mold half 19 fromthe extruder 11, (iv) using a plurality of gated plates 35 to vary thethickness across the width of the extruded material and in differentparts of the extruded material, and finally (v) extruding moltenthermoplastic material through the selected and adjusted extrusion dieto achieve a variable thickness in the part formed. Thus, the extrudergenerally provides a molten flow of thermoplastic composite materialthrough the dynamic die, gravitating onto a mold half or lower mold invariable quantities in the vertical plane and across both horizontaldirections on the mold.

[0070] The “extrusion-molding” process described above is ideal formanufacturing medium to large thermoplastic composite structuresreinforced with glass, carbon, metal or organic fibers to name a few.The extrusion-molding process includes a computer-controlled extrusionsystem that integrates and automates material blending or compounding ofthe matrix and reinforcement components to dispense a profiled quantityof molten composite material that gravitates into the lower half of amatched-mold, the movement of which is controlled while receiving thematerial, and a compression molding station for receiving the lower halfof the mold for pressing the upper half of the mold against the lowerhalf to form the desired structure or part. The lower half of thematched-mold discretely moves in space and time at varying speeds toenable the deposit of material more thickly at slow speed and morethinly at faster speeds. The thermoplastic apparatus 10 described aboveis one embodiment for practicing the extrusion-molding process.Unprocessed resin (which may be any form of regrind or pleatedthermoplastic or, optionally, a thermoset epoxy) is the matrix componentfed into a feeder or hopper of the extruder, along with reinforcementfibers greater than about one-half inch (½″) in length. The compositematerial may be blended and/or compounded by the extruder 11, and“intelligently” deposited onto the lower mold half 19 by controlling theoutput of the extruder 11 with the gates 35 and the movement of thelower mold half 19 relative to the position of the extruder 11, as willbe described below with the embodiments shown in FIGS. 6A and 6B. Inthose embodiments the lower section of the matched-mold is fastened on atrolley which moves discretely below the dynamic die. The lower sectionof the matched-mold receives precise amounts of extruded compositematerial, and is then moved into the compression molding station.

[0071] The thermoplastic matrix materials that may be utilized in theextrusion-molding processes to form the composite material includethermoplastic resins as understood in the art. The thermoplastic resinsthat may be utilized in accordance with the principles of the presentinvention may include any thermoplastic resin that can be melted andblended by the extruder 11. Examples of such thermoplastic resins areprovided in TABLE 1 with the understanding that the examples are notintended to be a complete list, and that other thermoplastic resins andmaterials may be utilized in producing the structural parts utilizingthe extrusion-molding system. Additionally the thermoplastic resins ofTABLE 1 may be used alone or in any combinations thereof. TABLE 1Thermoplastic Resins polyethylene polysulfone polypropylenepolyphenylene oxide polyvinyl chloride polybutylene terephthalatepolyvinylidene chloride polyethylene terephthlate polystyrenepolycyclohexane diethylene terephthalate styrene-butadiene-acrylonitrilepolybutylene naphthalate copolymer nylon 11 other polyesters used assoft segments nylon 12 thermotropic liquid crystal polymers nylon 6polyphenylene sulfide nylon 66 polyether ether ketones other aliphaticnylons polyether sulfones copolymers of aliphatic nylons polyetherimides further copolymerized with terephthalic acid or other aromaticdicarboxylic acids or aromatic diamines other aromatic polyamidespolyamide imides various copolymerized polyamides polyimidespolycarbonate polyurethane polyacetal polyether amidespolymethylmethacrylate polyester amides

[0072] Particular thermoplastic materials, including polypropylene,polyethylene, polyetheretherketone, polyesters, polystyrene,polycarbonate, polyvinylchloride, nylon, polymethyl, polymethacrylate,acrylic, polyurethane and mixtures thereof, have been especiallysuitable for the extrusion-molding process.

[0073] The fibers that serve as the reinforcement component for thethermoplastic composite materials generally include those materials thatmay be utilized to reinforce thermoplastic resins. Fiber materialssuitable for use in accordance with the principles of the presentinvention include, without limitation, glass, carbon, metal and naturalmaterials (e.g., flax, cotton), either alone or in combination. Otherfibers not listed may also be utilized as understood in the art.Although the diameter of the fiber generally is not limited, the fiberdiameter for molding larger structural parts generally ranges between 1and 20 μm. It should be understood, however, that the diameter of thefibers may be larger depending on a number of factors, includingstrength of structural part desired, density of fiber desired, size ofstructural part, etc. In particular, the effect of improvement ofmechanical properties is marked with a fiber having a diameter ofapproximately one (1) to approximately nine (9) μm.

[0074] The number of filaments bundled in the fiber also is notgenerally limited. However, a fiber bundle of 10,000 to 20,000 filamentsor monofilaments is generally desired for handling considerations.Rovings of these reinforcing fibers may be used after surface treatmentby a silane or other coupling agent. To improve the interfacial bondingwith the thermoplastic resin, for example, in the case of a polyesterresin, surface treatment may be performed by a thermoplastic filmforming polymer, coupling agent, fiber lubricant, etc. Such surfacetreatment may be performed in advance of the use of the treatedreinforcing fibers or the surface treatment may be performed just beforethe reinforcing fibers are fed into the extruder in order to run theextrusion process to produce the molten thermoplastic composite withoutinterruption. The ratio between the thermoplastic resin and fiber is notparticularly limited as it is possible to produce the thermoplasticcomposite and shaped articles using any ratio of composition inaccordance with the final object of use. However, to provide sufficientstructural support for the structural parts, as understood in the art,the content of fibers is generally five percent (5%) to fifty percent(50%) by weight. It has been determined that the content of fibers isgenerally ten (10) to seventy (70) percent by weight, and preferablyforty percent (40%) by weight to achieve the desired mechanicalproperties for the production of larger articles.

[0075] The average fiber length of the fibers is greater than aboutone-half inch (½″). However, typical structural parts produced by theextrusion-molding system 600 a utilize fiber lengths longer than aboutone inch. It should be noted that when the average fiber length is lessthan one inch, the desired mechanical properties for large articles isdifficult to obtain. Distribution of the fibers in the thermoplasticcomposite material is generally uniform so that the fibers andthermoplastic resin do not separate when melted and compressed. Thedistribution or disbursement of the fibers includes a process by whichthe fibers are dispersed from a single filament level to a level ofmultiple filaments (i.e., bundles of several tens of fibers). In oneembodiment, bundles of about five fibers are dispersed to provideefficiency and structural performance. Further, the “degree of combing”may be evaluated by observing a section of the structure by a microscopeand determining the ratio of the number of reinforcing fibers in bundlesof ten or more in all of 1000 or more observable reinforcing fibers(total number of reinforcing fibers in bundles of 10 or more/totalnumber of reinforcing fibers.times.100) (percent). Typical valuesproduced by the principles of the present invention result in not morethan approximately sixty percent (60%), and generally below thirty-fivepercent (35%).

[0076]FIG. 6A is an exemplary schematic diagram of an extrusion-moldingsystem 600 a operable to form structural parts. The extrusion-moldingsystem 600 a is composed of a number of discrete components that areintegrated to form structural parts from composite material. Thecomponents include a material receiving unit 602, a heater 618, anextruder 604, a dynamic die 606, a trolley 608, a compression press 610,and a controller 612. Other supplemental components may also be includedto form the extrusion-molding system 600 a.

[0077] The material receiving unit 602 may include one or more hoppersor feeders 614 and 615 for receiving materials M1 and M2, respectively,that will be extruded to form a thermoplastic composite. It should beunderstood that additional feeders may be utilized to receive additionalmaterials or additives to formulate different compounds. In the instantexample, materials M1 and M2 represent the starting material i.e.,reinforced thermoplastic materials preferably in the form of pellets. M1and M2 may be the same or different reinforced thermoplastic material.The thermoplastic materials may be reinforced by fibers, such as glassor carbon fibers, as understood in the art. It should be furtherunderstood that non-thermoplastic material may be utilized in accordancewith the principles of the present invention.

[0078] A heater 618 preheats the thermoplastic materials M1 and M2. Theextruder 604 is coupled to the feeder channel 616 and operable to mixthe heated thermoplastic materials M1 and M2 via an auger 620. Theextruder 604 further melts the thermoplastic materials. The auger 620may be helical or any other shape operable to mix and flow the compositematerial through the extruder 604. An extruder output channel 622 iscoupled to the extruder 604 and is utilized to carry the compositematerial to a dynamic die 606.

[0079] The dynamic die 606 includes multiple flow control elements 624a-624 n (collectively 624). The flow control elements 624 may beindividual gates, valves, or other mechanisms that operate to controlthe extruded composite material 625 from the dynamic die 606, where theextruded composite material 625 a-625 n (collectively 625) varies involumetric flow rates across a plane P at or below the flow controlelements 624. The outputting of the different volumetric flow ratesranges between approximately zero and 3000 pounds per hour. A morepreferable range for the volumetric flow rate ranges betweenapproximately 2500 and 3000 pounds per hour. In one embodiment, the flowcontrol elements 624 are gates that are raised and lowered by separateactuators, such as electrical motors, (e.g., stepper motors), hydraulicactuators, pneumatic actuators, or other actuator operable to alter flowof the composite material from the adjustable flow control elements 624,individually or collectively. The flow control elements 624 may beadjacently configured to provide for a continuous separating adjacentflow control elements 624. Alternatively, the flow control elements 624may be configured separately such that the composite material flowingfrom adjacent flow control elements 624 remains separated until thecomposite material spreads on a mold. It should be understood that theflow control elements 624 suitably may operate as a trimmer 17. In anembodiment of the invention, the molten composite material may bedelivered to an accumulator, placed between the extruder 604 and thedynamic die 606, from which the composite material may be delivered intoa lower mold using a plunger or other actuating mechanism.

[0080] The trolley 608 may be moved beneath the dynamic die 606 so thatthe extruded composite material 625 gravitates to or is deposited on alower mold 626, which passes below the dynamic die 606 at apredetermined vertical distance, the “drop distance” (d). The lower mold626 defines cavities 630 that are used to form a structural part. Theextruded composite material 625 is deposited 628 on the lower mold 626to fill the volume defined by the cavities 630 in the lower mold 626 andan upper mold 632 to form the composite part. In a two-axis controlledprocess, the composite material 625 a may be deposited on the lower mold626 at a substantially constant volumetric flow rate from the dynamicdie 606 or across a vertical plane (P), based on discrete movement andvariable speeds, to form the composite material layer 628 havingsubstantially the same thickness or volume along the vertical plane (P)to fill the cavities 630 in the lower and upper molds 626 and 632. In athree-axis controlled process, the composite material may be depositedon the lower mold 626 at different volumetric flow rates from thedynamic die 606 across the vertical plane (P) to form the compositematerial layer 628 having different thickness or volume along thevertical plane (P) to fill the cavities 630 in the lower and upper molds626 and 632. It should be understood that the two-axis controlledprocess may be utilized to deposit the composite material to molds thathave cavities 630 substantially constant in depth in the vertical planeand that the three-axis controlled process may be utilized to depositthe composite to molds that have cavities 630 that vary in depth.

[0081] The trolley 608 may further include wheels 634 that provide fortranslation along a rail 636. The rail 636 enables the trolley 608 toroll beneath the dynamic die 606 and into the press 610. The press 610operates to press the upper mold 632 into the lower mold 626. Eventhough the principles of the present invention provide for reduced forcefor the molding process than conventional thermoplastic moldingprocesses due to the composite material layer 628 being directlydeposited from the dynamic die 606 to the lower mold 626, the forceapplied by the press 610 is still sufficient to damage the wheels 634 ifleft in contact with the rail 636. Therefore, the wheels 634 may beselectively engaged and disengaged with an upper surface 638 of a base640 of the press 610. In an embodiment, the trolley 608 is raised byinflatable tubes (not shown) coupled thereto so that when the tubes areinflated, the wheels 634 engage the rails 636 so that the trolley 608 ismovable from under the die 606 to the press 610. When the tubes aredeflated, the wheels 634 are disengaged so that the body of the trolley608 is seated on the upper surface 638 of a base 640 of the press 610.It should be understood that other actuated structural components may beutilized to engage and disengage the wheels 634 from supporting thetrolley 608, but that the functionality to engage and disengage thewheels 634 is to be substantially the same. For example, the uppersurface 638 of the base 640 of the press 610 may be raised to contactthe base plate 642 of the trolley 608.

[0082] The controller 612 is electrically coupled to the variouscomponents that form the extrusion-molding system 600. The controller612 is a processor-based unit that operates to orchestrate the formingof the structural parts. In part, the controller 612 operates to controlthe composite material being deposited on the lower mold 626 bycontrolling temperature of the composite material, volumetric flow rateof the extruded composite material 625, and the positioning and rate ofmovement of the lower mold 626 via the trolley 608 to receive theextruded composite material 625. The controller 612 is further operableto control the heater 618 to heat the thermoplastic materials. Thecontroller 612 may control the rate of the auger 620 to maintain asubstantially constant flow of composite material through the extruder604 and into the dynamic die 606. Alternatively, the controller 612 mayalter the rate of the auger 620 to alter the volumetric flow rate of thecomposite material from the extruder 604. The controller may furthercontrol heaters (not shown) in the extruder 604 and the dynamic die 606.Based on the structural part being formed, a predetermined set ofparameters may be established for the dynamic die 606 to apply theextruded composite material 625 to the lower mold 626. The parametersmay be defined such that the flow control elements 624 may beselectively positioned such that the movement of the trolley 608 ispositionally synchronized with the volumetric flow rate of the compositematerial in accordance with the cavities 630 that the define thestructural part being produced.

[0083] The trolley 608 may further include a heater (not shown) that iscontrolled by the controller 612 and is operable to maintain theextruded composite material 625 in a heated or melted state. Thecontroller may, by varying the required speeds of the trolley, controlthe trolley 608 during extruded composite material 625 being applied tothe lower mold 626. Upon completion of the extruded composite material625 being applied to the lower mold 626, the controller 612 drives thetrolley 608 into the press 610. The controller then signals a mechanism(not shown) to disengage the wheels 634 from the track 636 as describedabove so that the press 610 can force the upper mold 632 against thelower mold 626 without damaging the wheels 634.

[0084]FIG. 6B is another exemplary block diagram of theextrusion-molding system 600 a of FIG. 6A. The extrusion-molding system600 b is configured to support two presses 610 a and 610 b that areoperable to receive the trolley 608 that supports the lower mold 626 toform the structural part. It should be understood that two trolleys 608may be supported by the tracks or rails 636 so as to provide for formingmultiple structural components by a single extruder 604 and dynamic die606. While wheels 634 and rails 636 may be utilized to provide movementfor the trolley 608 in one embodiment, it should be understood thatother movement mechanisms may be utilized to control movement for thetrolley 608. For example, a conveyer, suspension, or track drive systemmay be utilized to control movement for the trolley 608.

[0085] The controller 612 may be configured to support multiplestructural parts so that the extrusion-molding system 600 b maysimultaneously form the different structural parts via the differentpresses 610 a and 610 b. Because the controller 612 is capable ofstoring parameters operable to form multiple structural parts, thecontroller 612 may simply alter control of the dynamic die 606 andtrolleys 608 a and 608 b by utilizing the parameters in a generalsoftware program, thereby providing for the formation of two differentstructural parts using a single extruder 604 and dynamic die 606. Itshould be understood that additional presses 610 and trolleys 608 may beutilized to substantially simultaneously produce more structural partsvia a single extruder 604 and dynamic die 606.

[0086]FIG. 7 is an exemplary exploded view of the dynamic die 606depositing the extruded composite material 625 on the lower mold 626 assupported by the trolley 608. As shown, the dynamic die 606 includes themultiple flow control elements 624 a-624 i. It should be understood thatthe number of flow control elements 624 may be increased or decreaseddepending upon the resolution or detail of the structural part beingformed. As shown, the flow control elements 624 are positioned atdifferent heights so as to provide more or less volumetric flow rate ofthe extruded composite material 625 associated with each flow controlelement 624. For example, flow control element 624 a is completelyclosed, so as to prevent composite material from being passed throughthat section of the dynamic die 606. The volumetric flow rate f_(a) istherefore zero associated with the closed flow control element 624 a.The flow control element 624 b is opened to form an aperture having aheight h₁, thereby providing a volumetric flow rate f_(b) of theextruded composite material 625 b. Similarly, the flow control element624 c is opened to form a larger aperture for the extruded compositematerial 625 c to be output at a higher volumetric flow rate f_(c) ontothe lower mold 626.

[0087] As indicated by the variation in shading of the extrudedcomposite material 625 associated with each of the flow control elements624, the flow control elements 624 may be dynamically adjusted based onthe structural part being formed via the lower and upper molds 626 and632. Accordingly, based on the structural part being formed (e.g., deepdraw over a certain region), the flow control elements 624 may beadjusted to alter the volumetric flow rates of the extruded compositematerial 625 over finite regions of the lower and upper molds 626. Inother words, based on the cavities 630 defined by the lower and uppermolds 626 and 632, the composite material layer 628 may be varied inthickness. For example, the composite material layer region 628 a isthinner than composite material layer region 628 b, which is thicker tosufficiently fill the cavity 630 a, which has a deeper draft than otherlocations of the cavity 630 in the lower mold 626. In other words, theextruded composite material layer 628 is dynamically altered based onthe depth of the cavity 630 defined by the molds 626 and 632. In boththe two- and three-axis controlled processes capable of being performedon the extrusion-molding system 600 a, the extruded composite materiallayer 628 may be dynamically altered in terms of thickness based on thevolumetric flow rate of the extruded composite material 625 and thespeed of travel of the trolley 608.

[0088] Depositing the extruded composite material onto the lower moldmay be performed by controlling the amount of extruded compositematerial deposited in two or three axes depending on the structural partbeing produced. For the two-axis control, the movement of the trolleymay be controlled along the axis of movement to deposit the extrudedcomposite material in various amounts along the axis of deposit. For thethree-axis control, the output of the extruder may utilize a dynamic diethat includes flow control elements, thereby providing for differentvolumetric flow rates to be simultaneously deposited onto the lower moldalong the axis perpendicular to the axis of movement. It should beunderstood that other embodiments may provide for off-axis or non-axiscontrol to deposit the extruded composite material in specific locationson the lower mold.

[0089] By providing for control of the trolley and composite materialbeing applied to the lower mold, any pattern may be formed on the lowermold, from a thick continuous layer to a thin outline of a circle orellipse, any two-dimensional shape that can be described by discretemathematics can be traced with material. Additionally, because controlof the volume of composite material deposited on a given area exists,three-dimensional patterns may be created to provide for structuralcomponents with deep draft and/or hidden ribs, for example, to beproduced. Once the structural part is cooled, ejectors may be used topush the consolidated material off of the mold. The principles of thepresent invention may be designed so that two or more unique parts maybe produced simultaneously, thereby maximizing production efficiency byusing a virtually continuous stream of composite material.

[0090] Value-Added Benefits of the Extrusion-Molding Process

[0091] With the extrusion-molding system, large long-fiber reinforcedplastic parts may be produced in-line and at very low processing costs.Features of the extrusion system provide for a reinforced plasticcomponents production line that offers (i) materials flexibility, (ii)deposition process, (iii) low-pressures, and (iv) machine efficiency.Materials flexibility provides for savings in both material and machinecosts from in-line compounding, and further provides for materialproperty flexibility. The deposition process adds value in the materialdeposition process, which allows for more complicated shapes (e.g.,large draft and ribs), better material flow, and ease of inclusion oflarge inserts in the mold. The low-pressures is directed to reducedmolding pressures, which lessen the wear on both the molds and themachines, and locks very little stress into the structural parts. Themachine efficiency provides for the ability to use two or morecompletely different molds at once to improve the efficiency of theextrusion system, thereby reducing the required number of machines torun a production operation. Additionally, the material delivery systemaccording to the principles of the present invention may be integratedwith many existing machines.

[0092] Materials Flexibility

[0093] The extrusion-molding process allows custom composite blends tobe compounded using several different types of resin and fiber. Theextrusion system may produce parts with several resins as describedabove. With traditional compression molding, pre-manufacturedthermoplastic sheets, commonly known as blanks that combine a resin withfibers and desired additives are purchased from a thermoplastic sheetproducer. These blanks, however, are costly because they have passedthrough several middle-men and are usually only sold in pre-determinedmixtures. By utilizing the extrusion-molding process according to theprinciples of the present invention, these costs may be reduced by thein-line compounding process utilizing the raw materials to produce thestructural parts without having to purchase the pre-manufactured sheets.Labor and machine costs are also dramatically reduced because theextrusion-molding system does not require ovens to pre-heat the materialand operators to move the heated sheets to the mold. Since the operatorcontrols the compounding ratios as desired, nearly infinite flexibilityis added to the process, including the ability to alter properties whilemolding or to create a gradual change in color, for example. Also,unlike sheet molding, the extrusion-molding system does not require thematerial to have a melt-strength, giving the system added flexibility.In one embodiment, the extrusion-molding system may utilize thermosetresins to produce the structural parts. The extrusion-molding system mayalso use a variety of fiber materials, including carbon, glass and otherfibers as described above, for reinforcement with achievable fibervolume fractions of over 50 percent and fiber lengths of one to fourinches or longer with 85 percent or higher of the fiber length beingmaintained from raw material to finished part.

[0094] Deposition Process

[0095] The extrusion system, according to the principles of the presentinvention, allows for variable composite material lay-down; in regionsof the mold where more material is to be utilized for deep draft orhidden ribs, for example, thereby minimizing force utilized duringmolding and pressing. The variable composite material lay-down resultsin more accuracy, fuller molds, and fewer “short-shots” as understood inthe art than with typical compression molding processes. Variablelay-down also allows for large features to be molded on both sides ofthe structural part, as well as the placement of inserts or cores intothe structural part. Lastly, since the material has a relatively verylow viscosity as it is being deposited in a molten state onto the mold(as opposed to being pre-compounded into a sheet and then pressed into amold), fibers are able to easily enter ribs and cover large dimensionalareas without getting trapped or becoming undesirably oriented.

[0096] Low-Pressures

[0097] The thermoplastic composite material being deposited during theextrusion-molding process is much more fluid than that from a heatedpre-compounded sheet, thus allowing the thermoplastic composite materialto flow much easier into the mold. The fluidity of the compositematerial being deposited onto the mold results in significantly reducedmolding pressure requirements over most other molding processes. Pressesfor this process generally operate in the range of 100 pounds per squareinch, compared with 1,000 pounds per square inch of pressure used forcompression molding. This lower pressure translates to less wear,thereby reducing maintenance on both the molds and the press. Because ofthe lower pressures, instead of needing a steel tool that could costover $200,000, an aluminum mold, capable of 300,000 cycles, and may bemanufactured for as little as $40,000. Less expensive tooling also meansmore flexibility for future design changes. Since the thermoplasticresin is relocated and formed on the face of the mold under lowerpressures, less stress is locked into the material, thereby leading tobetter dimensional tolerance and less warpage.

[0098] Machine Efficiency

[0099] Because the extrusion-molding process may use two or more moldsrunning at the same time, there is a reduction in the average cycle timeper part, thus increasing productivity as the first mold set may becooled and removed while a second mold is filled and compressed. Also,the extrusion-molding system utilizes minimal redundant components. Inone embodiment, the extrusion system utilizes a separate press for eachmold, but other equipment may be consolidated and shared between themold sets and may be easily modified in software to accommodate othermolds. The extrusion and delivery system 600 a further may be integratedinto current manufacturing facilities and existing compression molds andpresses may be combined.

[0100]FIG. 8A is an exemplary flow diagram describing theextrusion-molding process that may be utilized to form articles orstructural parts by using either two- or three-axis control fordepositing the composite material onto the lower mold 626. Theextrusion-molding process starts at step 802. At step 804, thethermoplastic material is heated to form molten thermoplastic materialand blended with the fiber at step 802 to form a composite material. Atstep 708, the molten composite material is delivered through the dynamicdie to gravitate onto a lower mold 626. For the two-axis extrusiondeposit process, a fixed output from the die may be utilized. In atwo-axis process, the movement of the trolley is maintained at aconstant speed. In a three-axis extrusion control process, a dynamic die606 may be utilized in conjunction with varying trolley or mold speeds.For both the two- and three-axis extrusion control process, the lowermold 626 may be moved in space and time while receiving the compositematerial to conform the amount of composite material required in thecavity 630 defined by the lower and upper molds 626 and 632 at step 810.At step 812, the upper mold 632 is pressed to the lower mold 626 topress the composite material into the lower and upper molds 626 and 632.The process ends at step 814.

[0101]FIG. 8B is an exemplary flow diagram for producing structuralparts utilizing the extrusion-molding system 600 a of FIG. 6A via thethree-axis control extrusion-molding process. The structural partproduction process starts at step 816. At step 818, thermoplasticmaterial is received. The thermoplastic material is heated at step 822.In one embodiment, the thermoplastic material is heated to a melted ormolten state. At step 820, fibers having a predetermined fiber lengthare received. At step 822, the fibers are blended with the heatedthermoplastic material to form a composite material. The fibers may belong strands of fiber formed of glass or other stiffening materialutilized to form large structural parts. For example, fiber lengths ofone-half inch (½″) up to four inches (4″) or more in length may beutilized in forming the structural parts.

[0102] The composite material is extruded at step 826. In the extrusionprocess, the auger 620 or other mechanism utilized to extrude thecomposite material is configured to substantially avoid damaging thefibers such that the original fiber lengths are substantially maintained(e.g., 85 percent or higher). For example, in the case of using a screwtype auger 620, the thread spacing is selected to be larger than thelength of the fibers, thereby substantially avoiding damaging thefibers.

[0103] At step 828, the extruded composite material 625 may bedynamically output at different volumetric flow rates across a plane toprovide for control of depositing the extruded composite material 625onto the lower mold 626. The lower mold 626 may be positionallysynchronized to receive the extruded composite material 625 in relationto the different volumetric flow rates across the plane P at step 830.In an embodiment, the positional synchronization of the mold 626 isperformed in accordance with flow control elements 624 that are locatedat a height d above the trolley 608, which may be translated at asubstantially constant or adjustable rate. For example, to deposit aconstant or flat extruded composite material layer 628, the trolley 608is moved at a substantially constant rate, but to increase or decreasethe volume of the extruded composite material layer 628, the trolley 608may be moved at a slower or faster rate, respectively. At step 832, theextruded composite material 625 that is formed into the extrudedcomposite material layer 628 is pressed into the mold 626 to form thethermoplastic structural part. The structural part forming process endsat step 834.

[0104]FIG. 9 is an exemplary block diagram 900 of the controller 612 asconfigured to communicate with controllers operating within componentsof the extrusion system 600 a of FIG. 6A. The controller 612communicates with the various controllers for bi-directionalcommunication using digital and/or analog communication channels asunderstood in the art. The controllers operating within the componentsmay be processor based operating open or closed-loop control software asunderstood in the art and operate as slave computers to the controller612. Alternatively, the controllers may be non-processor basedcontrollers, such as analog or digital circuitry, that operate as slaveunits to the controller 612.

[0105] The feeder(s) 614 may include a speed and temperature controller902 that is operable to control speed and temperature of the feeder(s)614 for mixing the composite material M1 and fiber material M2. Thefeeder speed and temperature controller(s) 902 may be formed of singleor multiple controllers to control motor(s) and heater(s). Thecontroller 612 is operable to specify or command the velocity or rateand temperature of the feeder(s) 614, while the speed and temperaturecontroller 802 of the feeder(s) 614 is operable to execute the commandsreceived by the controller 812. For example, based on the amount ofcomposite material being extruded via the dynamic die 606, thecontroller 612 may increase the rate of the materials M1 and M2 beingfed into the extruder 606.

[0106] The controller 612 is further in communication with the heatercontroller 904. The controller 612 may communicate control data to theheater controller 904 based on feedback data received from the heatercontroller 904. For example, if the temperature of the heater controller904 decreases during feeding operations, then the controller 612 mayissue commands via the control data 1018 to the heater controller 904 toincrease the temperature of the heater 618. Alternatively, the heatercontroller 904 may regulate the temperature utilizing a feedbackregulator loop as understood in the art to the temperature commanded bythe controller 612 and simply report the temperature to the controller612 for monitoring purposes.

[0107] The controller 612 is further in communication with an extruderspeed and temperature controller 906, which provides control over thespeed of the auger 620 and temperature of the extruder 604. The extruderspeed and temperature controller 906 may be operable to control multipleheaters within zones of the extruder 604 and communicate thetemperatures of each heater to the controller 612. It should beunderstood that the extruder speed and temperature controller 906 may beformed of multiple controllers.

[0108] The controller 612 is further in communication with a dynamic diecontroller 908 that controls the flow control elements 624 of thedynamic die 606. The dynamic die controller 908 may operate to controleach of the flow control elements 624 collectively or individually.Alternatively, each flow control element 624 may be individuallycontrolled by separate controllers. Accordingly, the controller 612 mayoperate to issue commands to the dynamic die controller 908 to set theposition for each of the flow control elements 624 in an open-loopmanner. For example, a stepper motor may be utilized in an open-loopmanner. Actual position of each flow control elements 624 may becommunicated back to the controller 612 via the feedback data 1022 forthe controller 612 to utilize in controlling the positions of the flowcontrol elements 624.

[0109] The controller 612 is further in communication with a trolleycontroller 910 that is coupled to the trolley 608 and is operable tocontrol position of the trolley 608 and temperature of the lower mold626. The controller 612 may provide control signals 1018 to the trolleycontroller 910 that operates as a servo to drive the trolley 608 to thepositions commanded by the controller 612, which, in the case ofdepositing the extruded composite material 625 onto the lower mold 626,positions the lower mold 626 accordingly. Although the extrudedcomposite material layer 628 that is deposited onto the lower mold 626is molten at the time of deposition, the extruded composite materiallayer 628 deposited first tends to cool as the later extruded compositematerial 625 is being deposited. Therefore, the controller 612 maycommunicate control data 1018 to the trolley controller 910 to maintainthe temperature of the extruded composite material layer 628, either ata substantially constant temperature, based on time of deposition of theextruded composite material 625, and/or based on other factors, such asthermoplastic material M1 molten state temperature requirements.Feedback data 1022 may provide current temperature and status of theposition and velocity of the trolley 608 and temperature of the lowermold 626 so that the controller 612 may perform management andmonitoring functions.

[0110] The controller 612 is further in communication with a heat/coolcontroller 912, which is operable to control temperature of heatersand/or coolers for the extrusion-molding system 600 a. The heat/coolcontroller 912 may receive the control data 1018 from the controller 612that commands the heat/cool controller 912 to operate at a specific orvariable temperature based on a number of factors, such as thermoplasticmaterial M1, ambient temperature, characteristics of structural partbeing produced, production rates, etc. The heat/cool controller 912 maycontrol system-level heaters and coolers or component-level heaters andcoolers. Feedback data 1022 may provide current temperature and statusof the heaters and coolers so that the controller 612 may performmanagement and monitoring functions.

[0111] The controller 612 is further in communication with a presscontroller 914, which is operable to control press operation andtemperature of the upper mold 632. The press controller 914 may be astandard controller that the manufacturer of the press 610 supplies withthe press 610. Similarly, the press controller 914 may include atemperature controller to control the temperature of the upper mold 932.Alternatively, the temperatures controller may not be associated withthe press controller 914 provided by the manufacturer of the press 910.Feedback data 612 may provide current position and force of the pressand temperature of the upper mold 632 so that the controller 612 mayperform management and monitoring functions.

[0112] The controller 612 is further in communication with an extractiontool controller 916 that is operable to control extraction operations ona molded structural component. In response to the controller 612receiving notification from the press controller 914 that the press 610has completed pressing operations, the controller 612 may issue controlsignals 1018 to the extraction tool controller 916 to initiateextraction of the molded structural component. Accordingly, feedbackdata 1022 may be utilized to indicate current operation of theextraction tool. If the feedback data 1022 indicates that the extractiontool is having difficulty extracting the molded structural component, anoperator of the extrusion-molding system 600 a may be notified that aproblem exists with the extraction tool, the lower or upper molds 626and 632, the press 610, the heater or cooler of the upper or lower mold626 and 632, or other component or function of the extrusion-moldingsystem 600 a.

[0113] It should be understood that while the controller 612 may beconfigured to be a master controller for each of the components of theextrusion-molding system 600 a, that the controller 612 may beconfigured to manage the components in a more distributed controllermanner. In other words, the controllers of the components may operate asmore intelligent controllers that use the parameters of the structuralparts being produced to compute operating and control parameters andless as servos that are commanded by the controller 612 to perform afunction. It should be further understood that the controller 612 may beprogrammed to accommodate different mechanical configurations of theextrusion-molding system 600 a. For example, if the extrusion-moldingsystem 600 a were configured such that the output of the extruder 606translated or otherwise moved relative to a stationary lower mold 626,which may or may not be coupled to a trolley 608, then the controller612 may be programmed to control the movement of the output of theextruder 606 rather than movement of the trolley 608.

[0114]FIG. 10 is an exemplary block diagram of the controller 612 ofFIG. 6A. The controller 612 includes a processor 1002 coupled to amemory 1004 and user interface 1006. The user interface 1006 may be atouch screen, electronic display and keypad, pen-based interface, or anyother user interface as understood in the art. The processor 1002 isfurther coupled to an input/output (I/O) unit and a storage unit 1010that stores information in databases or files 1012 a-1012 n(collectively, 1012). The databases 1012 may be utilized to storecontrol parameters for controlling the extrusion-molding system 600 a,such as data associated with the lower and upper molds 626 and 632. Thedatabases 1012 additionally may be utilized to store data fed-back fromthe extrusion system 600 a during operation thereof.

[0115] The processor 1002 is operable to execute software 1014 utilizedto control the various components of the extrusion-molding system 600 aand to manage the databases 1012. In controlling the extrusion-moldingsystem 600 a, the software 1014 communicates with the extrusion-moldingsystem 600 a via the I/O unit 1008 and control bus 1016. Control data1018 is communicated via data packets and/or analog control signalsacross a control bus 1016 to the extrusion-molding system 600 a. Itshould be understood that the control bus 1016 may be formed of multiplecontrol busses, whereby each control bus is associated with a differentcomponent of the extrusion-molding system 600 a. It should be furtherunderstood that the control bus 1016 may operate utilizing a serial orparallel protocol.

[0116] A feedback bus 1020, which may be a single or multiple busstructure, is operable to feedback data 1022 from the extrusion-moldingsystem 600 a during operation. The feedback data 1022 may be sensorydata, such as temperature, position, velocity, level, pressure or anyother sensory information measured from the extrusion-molding system 600a. Accordingly, the I/O unit 1008 is operable to receive the feedbackdata 1022 from the extrusion-molding system 600 a and communicate thefeedback data 1022 to the processor 1002 to be utilized by the software1014. The software 1014 may store the feedback data in the database 1012and utilize the feedback data 1022 to control the components of theextrusion-molding system 600 a. For example, in the case of thetemperature of the heater being fed-back by the heater controller 904 tothe controller 612, if the temperature of the heater 618 becomes toolow, then the controller 612 may issue a command via the control data1018 to the heater 618 to increase the temperature thereof. Thecontroller 612 or component (e.g., heater) may include an automaticcontrol system as understood in the art for performing the control andregulation of the component.

[0117] In operation, the controller 612 may store control parameters forproducing one or more structural parts by the extrusion-molding system600 a. For example, data associated with parameters of the molds 626 and632, such as dimensions of the cavities 630, may be stored in thedatabase 1012. By storing multiple sets of parameters for variousstructural parts, the extrusion-molding system 600 a may be utilized toform the structural parts substantially simultaneously. The processor1002 may execute the software 1014 with the different sets of parametersin parallel to form the structural parts substantially simultaneously.That is, when one structural part is being pressed, another may beformed via the dynamic die 606 by applying the extruder compositematerial 625 onto the lower mold 626.

[0118]FIG. 11 is an exemplary block diagram of the software 1014 that isexecuted by the processor 1002. A system manager 1100 is operable tomanage various aspects of the controller 612. The system manager 1100interfaces with an operator interface 1102, system drivers 1104, and adatabase manager 1106.

[0119] The operator interface 1102 is utilized to provide an interfacefor an operator of the extrusion-molding system 600 a to control theextrusion-molding system 600 a manually or establish programs and/orprofiles for producing structural parts. The operator interface 1102communicates with a program selector 1108, which, when previouslyprogrammed, allows the operator to select programs for producing thestructural parts. For example, a program that is established to producea pallet may be selected via the operator interface 1102 by an operatorso as to control the extrusion-molding system 600 a to produce thepallet as defined by a designer of the pallet in accordance with thelower and upper molds 626 and 632. In one embodiment, the programselector 1108 merely selects a generic program that produces specificstructural parts by controlling the extrusion-molding system 600 a byutilizing a specific sets of parameters for controlling the componentsaccordingly. The program selector 1108 may communicate with a parameterselector/editor 1110 that allows the operator to select a particular setof parameters to form a particular structural part and/or edit theparameters to alter the process for forming the structural part. Theparameter selector/editor 1110 may interface with the database manager1106 for selecting a particular set of parameters from a variety ofdifferent parameter datafiles available for the controller 612 to drivethe components of the extrusion-molding system 600 a to form differentstructural parts. For example, the database manager 1106 may have accessto a set of parameters for producing a pallet, I-beam, backboard, etc.It should be understood that each of the components of theextrusion-molding system 600 a may be controlled by generic drivers andthat the parameters selected for producing a structural part may alterthe behavior of each of the components of the extrusion-molding system600 a accordingly.

[0120] The system drivers 1104 may be utilized to integrate with thecomponents of the extrusion-molding system 600 a as understood in theart. For example, individual system drivers 1104 may be utilized tocontrol the feeders 614, heater 618, extruder 604, dynamic die 606,trolley 608, and press 610. The system drivers 1104 may be customized bythe operator of the extrusion-molding system 600 a or be a genericdriver provided by a manufacturer of a particular component, such as thepress 610. During operation of the extrusion-molding system 600 aproducing a structural part, the system drivers 1104 may utilize theparameters selected to produce the structural part to drive thecomponents of the extrusion-molding system 600 a.

[0121] In controlling the components of the extrusion-molding system 600a, a database 1012 and status alert feedback manager 1114 are utilizedto provide feedback control for each of the components of theextrusion-molding system 600 a. For example, the heater 618 may feedbackthe actual temperature via a temperature sensor (not shown). Based onthe measured temperature of the heater 618, a system driver 1104utilized to control the heater 618 may increase or decrease thetemperature of the heater 618 in accordance with the actual temperaturemeasurement. Accordingly, other sensors may be utilized to feedbacktemperature, pressure, velocity, weight, position, etc., of eachcomponent and/or composite material within the extrusion-molding system600 a. In the case of a critical failure of a component, alerts may befed-back to the controller 612 and detected by the status alert feedbackmanager 1114. If an alert is deemed to be a major failure, the systemdrivers 1104 may shut down one or more components of theextrusion-molding system 600 a to prevent damage to hardware or personalinjury to an operator. In response to such an alert, the system manager1100 may trigger the operator interface 1102 to display the failure andprovide notice as to corrective actions or otherwise.

[0122]FIG. 12 is an exemplary schematic of the flow control elements 624a-624 f and lower mold 626, which is sectioned into a grid 1202. Thegrid spacings are defined by the flow control elements 624 along they-axis (identified as spacings 1-5) and defined by spacings a-e alongthe x-axis. It should be understood that a higher resolution for thegrid may be attained by utilizing more flow control elements 624 alongthe y-axis and defining smaller spacings along the x-axis. Dependingupon the particular structural part being formed, higher or lowerresolutions may be desired and parameters established by the operator todefine the higher or lower resolutions may be stored in the controller612 via the database manager 1106 for use in producing the structuralparts.

[0123] TABLES 2-10 are exemplary data tables that are utilized tocontrol the components of the extrusion-molding system 600 a.Specifically, the tables provide for the control data 1018 forcontrolling the components and feedback data 1022 received by thecontroller 612 from the components. TABLE 2 provides for control of thefeeders 614 that are used to feed thermoplastic composite material M1,fiber material M2, and any other materials (e.g., color) to form thestructural parts. As shown, the control data 1018 includes the rate thateach feeder 614 is delivering material to the extrusion-molding system600 a and the feedback data 1022 includes the level of the materialcurrently in each feeder 614. During operation of the extrusion-moldingsystem 600 a, the rate of the material being delivered from the feeder614 is controlled and level of the material in the feeders 614 ismeasured, the operator may be notified of the level of the material inresponse to the in the feeder 614 reaching a minimum amount so that theoperator may apply additional material to the feeder 614. TABLE 2Material Feeders Control Data Feedback Data Rate of Feed Material 1Level of Material 1 Rate of Feed Material 2 Level of Material 2 Rate ofFeed Material 3 Level of Material 3 . . . . . . Rate of Feed Material nLevel of Material n

[0124] TABLE 3 is an exemplary table that provides for temperaturecontrol for heaters in the extruder 604. In the case that the extruder604 is defined as having seven temperature zones 1-n, the temperaturesfor each zone may be set by the extruder temperature control beingdefined as being set to heat or cool, on or off, and/or a specifictemperature (not shown). The feedback data 1022 may include the actualtemperature of each zone of the extruder 604. Accordingly, temperaturesensors are integrated into each zone of the extruder 604 and thetemperatures sensed are fed-back via the feedback bus 1020 to thecontroller 612 for feedback control. TABLE 3 Extruder TemperatureControl Control Data Extruder Temperature Zone Control On/Off FeedbackData 1 Heat/Cool On/Off Actual Temp 2 Heat/Cool On/Off Actual Temp 3Heat/Cool On/Off Actual Temp . . . . . . . . . . . . 7 Heat/Cool On/OffActual Temp

[0125] TABLE 4 is an exemplary table that provides for speed control fora motor (not shown) driving the auger 620 operating in the extruder 604.The control data 1018 includes a speed control setting to drive themotor. Actual speed and load of the motor are fed-back via the feedbackdata 1022 to the system driver 1104 utilized to control the rate of theauger 620 extruder 604 via the control data 1018. TABLE 4 Extruder MotorControl Control Data Feedback Data Speed Control Signal Actual Speed ofMotor Actual Load of Motor

[0126] TABLE 5 defines the temperature control for heaters in thedynamic die 606. The control data 1018 may be defined by zones 1-nwithin the dynamic die 606. Similar to the temperature control of theextruder 604, the heater 618 may include heating and cooling controlsand/or on and off settings for controlling and/or regulating thetemperature of the different zones within the dynamic die 606.Accordingly, the feedback data 1022 may include the actual temperaturefor each of the zones within the dynamic die 606 for control thereof.TABLE 5 Dynamic Die Temperature Control Control Data Dynamic Die ZoneTemp Control On/Off Feedback Data 1 Heat/Cool On/Off Actual Temp 2Heat/Cool On/Off Actual Temp 3 Heat/Cool On/Off Actual Temp . . . . . .. . . . . . N Heat/Cool On/Off Actual Temp

[0127] TABLE 6 is an exemplary table for control of the flow controlelements 624 of the dynamic die 606. As shown, the control data includesflow control elements 1-n and positions for each flow control element624 ranging from 1-m. It should be understood that the flow controlelements 624 may have a nearly infinite number of positions. However,for practical purposes, the flow control element positions are typicallyset to have certain predetermined positions, such as each quarter-inchranging from zero to six inches, for example. In controlling thepositions of the flow control elements 624, a stepper motor or othertype of motor may be utilized. Accordingly, the feedback data 1022 forthe flow control elements 624 include the current positions of the flowcontrol elements 624 so that any deviation of position between thecontrol data 1018 communicated by the controller 612 to the dynamic die606 may be corrected by a feedback loop via the feedback data 1022 asunderstood in the art. TABLE 6 Dynamic Die Flow Control Element ControlControl Data Flow Control Element Position Feedback Data 1 Position 1-mCurrent Position 2 Position 1-m Current Position 3 Position 1-m CurrentPosition . . . . . . . . . N Position 1-m Current Position

[0128] TABLE 7 is an exemplary table that provides for temperaturecontrol for the lower mold 626. It should be understood that a similartable may be utilized to control the temperature of the upper mold 632.As shown, the lower mold 626 may be segmented into a number of zones1-n, where heaters and/or coolers may be applied to each zone to heatand cool the lower mold 626 as commanded by the control data 1018.Accordingly, feedback data 1022 may provide for the actual temperatureof the lower mold 626 so that feedback control may be performed by thecontroller 612 to regulate the temperature of the lower mold 626. Forexample, as the extruded composite material 625 is applied to the lowermode 626, the temperature of the lower mold 626 may be regulated acrossthe zones to regulate the temperature of the extruded composite materiallayer 628 based on time and other factors as the composite material isdeposited onto the lower mold 626 and until the structural part isremoved from the molds 626 and 632. TABLE 7 Heat/Cool Mold ControlControl Data Mold Temp Zone Control On/Off Feedback Data 1 Heat/CoolOn/Off Actual Mold Temp 2 Heat/Cool On/Off Actual Mold Temp 3 Heat/CoolOn/Off Actual Mold Temp 4 Heat/Cool On/Off Actual Mold Temp . . . . . .. . . . . . N Heat/Cool On/Off Actual Mold Temp

[0129] TABLE 8 is an exemplary table that provides exemplary controlparameters for controlling the trolley 608. As shown, the control data1018 includes position, speed, and lift control for the trolley 608. Itshould be understood that additional control data 1018 may be includedto control motion of the trolley 608. For example, acceleration,rotation or angular position, or other dynamic control data may beutilized to move or synchronize the trolley 608 to properly align thelower mold 626 with respect to the application of the extruded compositematerial 625 being deposited or gravitated onto the lower mold 626. Thefeedback data 1022 for the trolley 608 may include actual position andcurrent speed of the trolley 608. The lift control data may be utilizedto engage and disengage the wheels 634 of the trolley 608 both duringdepositing of the extruded composite material 625 to the lower mold 626and pressing the extruded composite material layer 628 into the molds626 and 632 via the press 610, respectively. The actual position of thelift may be fed-back so as to ensure that the press 610 is not activateduntil the wheels 634 are disengaged via the lift mechanism (e.g., airtubes). TABLE 8 Trolley Control Control Data Feedback Data PositionControl Data Actual Position of Trolley Speed Control Data Current Speedof Trolley Lift Control Data Actual Position of Lift

[0130] TABLE 9 is an exemplary table that provides for control of thepress 610. The control data 1018 may include lock control data and cyclepress time. The feedback data 1022 may include position of the trolley608 in the press 610 and position of the press platen. Other control andfeedback parameters additionally may be included to control the press.For example, temperature control of the upper mold 632, force of thepress 610, etc., may also be included. TABLE 9 Press Control ControlData Feedback Data Lock Control Data Trolley Position in Press CyclePress Time Position of Press Platen

[0131] TABLE 10 provides an exemplary table for control of an extractiontool (not shown) for extracting a formed structural part from the molds626 and 632 after completion of the pressing and, optionally, coolingprocesses in forming the structural part. The control data 1018 mayinclude a start extraction cycle and feedback data 1022 may include asingle extraction tool position. It should be understood that multipleextraction tools or elements of an extraction tool may be utilized andother sensory feedback data may be sensed and fed-back to the controller612. TABLE 10 Extraction Tool Control Control Data Feedback Data StartExtraction Cycle Extraction Tool Position

[0132]FIG. 13 is a top view of the flow control elements 624 a-624 i asaligned to deposit the composite material onto the lower mold 626 ofFIG. 6A. As shown, the flow control elements 624 are positioned alongthe y-axis, which provides for three-axis control for depositing theextruded composite material 625 onto the lower mold 626. Accordingly,the x-axis control for depositing the extruded composite material 625may be provided by control of the movement of the trolley 608 atdifferent speeds below the flow control elements 624, the y-axis controlfor depositing the extruded composite material 625 may be provided bythe adjustment of the flow control elements 624, and the z-axis controlfor depositing the extruded composite material 625 may result fromcontrolling the deposition of the extruded composite material 625 alongthe x- and y-axes.

[0133] Control for depositing the extruded composite material 625 alongthe x-, y-, and z-axes may be performed using a variety of techniques,including: (1) controlling the volumetric flow rate of the compositematerial from the extruder 604 via the rate of rotation of the auger620; (2) controlling the rate of movement of the trolley 608 in a singleaxis; (3) controlling the aperture of the output of the extruder 604having a single flow control element 624 or multiple flow controlelements 624 operating uniformly; (4) individually controlling themultiple flow control elements 624; and (5) controlling motion of thetrolley 608 in multiple axes. Each of these techniques assume that othervariables are held constant. For example, technique (1) assumes that theoutput aperture of the extruder 604 is fixed and that the trolley 608travels at a constant rate below the output aperture. Technique (2)assumes that the volumetric flow rate of the composite material from theextruder 604 is constant and that the output aperture of the extruder604 is fixed. It should be understood, however, that the techniques maybe combined to provide additional control of the placement of theextruded composite material 625 onto the lower mold 626 as discussedwith regard to FIG. 6A, where techniques (1), (2), and (4) are combined.Technique (5) includes providing not only x-axis and y-axis control overlower mold 626, but also z-axis and rotation about any number of axes.By providing such control over the lower mold 626 using technique (5), avariety of structural parts may be formed that may not be possibleotherwise. In sum, the overall computer control of the various elementsof the inventive process serves a critical role in the coordination ofthe extrusion process and the production of a desired part and theoverall operability of the process.

[0134] Finally, rather than controlling movement of the lower mold 626,the extruded composite material 625 may be deposited onto a stationaryor moving lower mold 626 using moving output apertures from the extruder604. For example, output apertures traveling along rails or othermechanical structure may be controlled to deposit the composite materialin specific locations on the lower mold 626. An analogy for such amechanism is a laser jet printer.

[0135] Referring again to FIG. 13, the flow control elements 624 areshown in relation to the lower mold 626 as it passes under the dynamicdie 606 and the numbers of the right side correspond with the positionof the trolley 608 in inches as it passes under the dynamic die 606. Thelower mold 626 starts ten inches into the trolley 608 due to the lowermold 626 being smaller than the trolley 608. TABLES 11-12 are exemplarytables that provide parameters for speed and gate control for the flowcontrol elements 624. The parameters may be utilized to produce thepallet utilizing the extrusion-molding system 600 a. TABLE 11 TrolleySpeed Control Parameters Start End Zone Control (%) Rate (ft/min)Position (inches) Position (inches) 1 0.50 6.67  0.0 10.0 2 2.00 1.6710.0 15.0 3 1.00 3.33 15.0 27.0 4 2.00 1.67 27.0 33.0 5 1.00 3.33 33.045.0 6 2.00 1.67 45.0 50.0

[0136] TABLE 12 Flow Control Element Parameters Start End Gate ZoneHeight (inches) Position (inches) Position (inches) 1 1 0.00 0.0 50.0 21 0.00 0.0 10.0 2 2 1.00 10.0 15.0 2 3 0.50 15.0 27.0 2 4 1.00 27.0 33.02 5 0.50 33.0 45.0 2 6 1.00 45.0 50.0 3 1 0.00 0.0 10.0 3 2 0.50 10.015.0 3 3 0.00 15.0 27.0 3 4 0.50 27.0 33.0 3 5 0.00 33.0 45.0 3 6 0.0045.0 50.0 4 1 0.00 0.0 10.0 4 2 0.50 10.0 15.0 4 3 0.00 15.0 27.0 4 40.50 27.0 33.0 4 5 0.00 33.0 45.0 4 6 0.00 45.0 50.0 5 1 0.00 0.0 10.0 52 1.00 10.0 15.0 5 3 0.50 15.0 27.0 5 4 1.00 27.0 33.0 5 5 0.50 33.045.0 5 6 1.00 45.0 50.0 6 1 0.00 0.0 10.0 6 2 0.50 10.0 15.0 6 3 0.0015.0 27.0 6 4 0.50 27.0 33.0 6 5 0.00 33.0 45.0 6 6 0.00 45.0 50.0 7 10.00 0.0 10.0 7 2 0.50 10.0 15.0 7 3 0.00 15.0 27.0 7 4 0.50 27.0 33.0 75 0.00 33.0 45.0 7 6 0.00 45.0 50.0 8 1 0.00 0.0 10.0 8 2 1.00 10.0 15.08 3 0.50 15.0 27.0 8 4 1.00 27.0 33.0 8 5 0.50 33.0 45.0 8 6 1.00 45.050.0 9 1 0.00 0.0 50.0

[0137] TABLES 11 and 12 provide for the positional synchronizationbetween the flow control elements 624 and the movement of the trolley608. By orchestrating the movement between the two components (i.e.,dynamic die 606 and trolley 608), the extruded composite material 625may be deposited at positions along the lower mold 626 as specified bythe volume of the cavities 630 of the lower and upper molds 626 and 632.In other words, the extruded composite material 625 is deposited ontothe lower mold 626 to form the extruded composite material layer 628thick enough to fill the cavities 630 of the lower and upper molds 626and 632, thereby providing the ability to form deep drafts and hiddenribs in certain locations of structural parts.

[0138]FIG. 14 is an exemplary perspective top view of a corner of apallet 1400 produced by the extrusion-molding system 600 a of FIG. 6A.As shown, the draft or depth d.sub.1 of the base 1402 of the pallet 1400is shallower than the depth d2 of a foot 1404 of the pallet 1400. Bycontrolling the deposition of the extruded composite material 625 ontothe lower mold 626 utilizing the principles of the present invention,large structural parts having features, such as the foot 1404, having adeeper draft d.sub.2 in specific regions of the structural parts may beformed using stiffener material M2 (e.g., long-strand fibers).

[0139]FIGS. 15A and 15B are an exemplary perspective bottom and topviews, respectively, of a platform 1500 having hidden ribs 1502 a-1502 e(collectively 1502). As shown, the hidden ribs 1502 are variable inheight, but have a definite volume over one or more zones. Therefore, bydepositing more extruded composite material 625 over the zones havingthe hidden ribs 1502 and less extruded composite material 625 over thezones without the hidden ribs 1502. Because the platform 1500 is formedas a single molded composite structure using the extrusion-moldingsystem 600 a, the platform 1500 has fewer weaknesses in the structurecompared to a platform that is formed of multiple parts.

[0140] Insertion Techniques

[0141] In addition to forming structural parts using composite materialhaving fibers blended therein to provide strength in forming largeparts, some structural parts further are structurally improved by havingother components, such as attachments, fasteners, and/or stiffeners,inserted or embedded in certain regions. For example, structural partsthat are to provide interconnectivity may utilize metallic partsextending from the composite material to provide strong and reliableinterconnections. One such structural part is a portion of a floorcovering 1600 for an ice rink, as depicted in FIG. 16A. The floorcovering 1600 includes the thermoplastic material 1602, which may beformed of the thermoplastic material M1 and fibers M2, and a fastener1604, which is formed of metal.

[0142] In forming the floor covering 1600, the fastener 1604 ispositioned or configured in the lower mold 608 so that the extrudedcomposite material layer 628 forms a bond layer 1606 with the fastener1604 to maintain the position thereof. To further secure the fastener1604 to the floor covering 1600, holes (not shown) may be included inthe fastener 1604 to allow the extruded composite material layer 628 tofill in the holes. During the formation process, actuators may beconfigured in the lower mold 626 to maintain the position of thefastener 1604 during the extrusion-molding process and released via thecontroller 612 while the extruded composite material layer 628 is stillin molten form. It should be understood that the fastener 1604alternatively may be configured in the upper mold 632.

[0143]FIG. 16B is an exemplary portion of a backboard 1610 that is oftenused by paramedics. The backboard 1610 is formed of composite material1612 and includes an insert 1614 encapsulated in the composite material1612. The insert 1614 may be a carbon fiber tube so that the backboard1610 may be stiffened, lightweight, and x-ray transparent. Inencapsulating the insert, the lower mold 626 may have actuators orsimple pins maintain the insert 1614 in place while the extrudedcomposite material layer 628 forms a bond layer 1616 therewith. Again,while the extruded composite material layer 628 is in a molten state,the actuators and/or pins may be released such that the extrudedcomposite material layer 628 fills in any voids left from the actuatorsor pins. It should be understood that the insert 1614 may besubstantially any material based on the particular application orstructural part being formed.

[0144]FIG. 17 is an exemplary flow diagram 1700 describing theoperations for embedding or inserting an insert, such as a fastener,support, or other element, into a structural part utilizing theextrusion-molding system 600 a of FIG. 6A. The insertion process startsat step 1702. At step 1704, the insert is configured in either the loweror upper mold 626 or 632. At step 1706, the molten extruded compositematerial 625 is deposited on the lower mold 626. The extruded compositematerial is formed about at least a portion of the insert at step 1708to secure the insert into the structural part being formed. In oneembodiment, the insert is encapsulated or completely embedded in theextruded composite material 625 (see, for example, FIG. 16B).Alternatively, only a portion of the insert is embedded in the extrudedcomposite material 625 so that a portion extends from the structuralpart.

[0145] At step 1710, if any supports are used to configure the insert inthe lower 626 or upper 632 mold, then the supports are removed. Thesupports, which may be actuator controlled, simple mechanical pins, orother mechanism capable of supporting the insert during deposition ofthe extruded composite material 625 onto the lower mold 626, are removedbefore the extruded composite material layer 628 is hardened at step1712. The extruded composite material layer 628 may be hardened bynatural or forced cooling during pressing, vacuuming, or other operationto form the structural part. By removing the supports prior to theextruded composite material layer 628 being hardened, gaps produced bythe supports may be filled in, thereby leaving no trace of the supportsor weak spots in the structural part. At step 1714, the structural partwith the insert at least partially embedded therein is removed from themold 626 and 632. The insertion process ends at step 1716.

[0146] In another embodiment of the invention, an insert is encapsulatedby a process of the claimed invention. In a manner analogous to theprocess described in FIG. 17, an insert, such as a fastener, support, orother element, may be encapsulated with extruded thermoplastic materialutilizing the claimed extrusion-molding system. In other embodiments ofthe invention, multiple layers of material of varying thickness may bedeposited one on top of the other utilizing the claimedextrusion-molding system. Specifically, a first layer of thermoplasticmaterial is extruded into a lower mold, following which a second layerof the same or different thermoplastic material is layered on top of thefirst layer. In certain embodiments of the invention, an insert may beplaced on top of the first extruded layer prior to or instead oflayering the first layer with a second extruded layer. This form of“layering” can facilitate the formation of a structure having multiplelayers of thermoplastic material, of the same or different composition,and layers of different inserted materials.

[0147] Advantageously, the present invention permits molding of articleshaving solid raised three-dimensional features. A non-limiting list ofthese raised features are blind ribs, posts, mounting posts, and tabs.

[0148] The articles may optionally have internal reinforcing inserts toprovide additional stability and strength. Examples of reinforcinginserts are tubes, rods, and mesh, although any kind of internal supportstructure can be used to provide the reinforcement. The reinforcinginserts can have any type of geometry or structure. For example, thecross-sectional appearance of the reinforcing inserts can be circular,hemispherical, star-shaped, or square, without restriction. Thereinforcing inserts can also be formed from any kind of material, suchas carbon, metals, synthetics, plastics, or organic substances such aswood.

[0149] The invention can be used to obtain large items, such as itemslonger than 0.5 feet in at least one of the z-, y-, and z-planes. Inparticular embodiments, large articles having dimensions longer than 1foot, 2 feet, and 3 feet can be obtained. The large articles can also beheavy, and can have weight greater than 10 lbs. In particularembodiments, articles with weights greater than 20 lbs or 25 lbs can beprepared.

[0150] Additional embodiments of the invention will be apparent from theExamples provided below.

EXAMPLE 1

[0151] In an embodiment of the current invention, Polypropylene resin(COP3541) from General Polymers was compounded using a single screw, 4½″diameter extruder (equipped with six heating zones and a standard PETscrew) with ½″ long fiberglass fiber (740DS) from Johns-Manville. Theresin/glass mixture consisted of 70% polypropylene and 30% glass. Theextruder zones were electrically heated and controlled at the followingtemperatures: Zone 1@350 F; Zone 2@375 F; Zone 3@400 F; Zone 4@450 F;Zone 5@475 F; Zone 6@505 F. A coupling agent (Polybond) was added to theglass resin mixture at the level of 2% to enhance bonding of the glassfibers to the resin matrix.

[0152] The heated mixture was passed by means of an unobstructedtransfer pipe to a heated multi-gated, horizontally mounted sheetextrusion die with independently controlled gates capable of varying thethickness of the polymer melt extruded through each gate. The moltenmixture was maintained at 505° F. within the gated die throughout theextrusion process. The molten resin/glass extrudate was gravitydeposited onto the horizontally moveable and heated half of a matchedmold. The deposition of the molten mixture was controlled by acombination of opening and closing of the gates on the horizontallymounted sheet die coupled with the controlled movement of thehorizontally mounted half of the matched die. The opening and closing ofthe gates on the die and the movement of the matched mold half duringthe extrusion process was accomplished using a computer program andelectrical controls to orchestrate the precise width, length and depthof the molten material deposited at each point on the surface of themoveable mold. In so doing, the resulting molten material deposited intothe mold represents a molten “net near shape” laydown of the desiredfinal molded product.

[0153] Upon completion of the “near net shape” molten deposition of theresin/glass mixture, the filled half of the matched mold is mechanicallytransferred by means of a trolley system to a compression press forfinal consolidation of the molded part. Since the filled half of themold represents a “near net shape” of the final molded part, the finalcompression molding step with the other half of the matched mold can beaccomplished at very low pressures (<2000 psi) and with minimal movementof the molten resin/glass mixture. Accordingly, the female portion of arectangular matched mold with an internal cavity measuring 12″ wide by24″ long and ¼″ deep was filled with the molten polypropylene/glassmixture described above in a “near net shape” laydown. The filled femaleportion of the mold was transferred mechanically to a 300 ton, Whitepneumatic compression press equipped with an 8′ by 9′ platen and an airbag bladder. The male half of the matched mold was compressed onto thefilled female half of the matched mold in a final molding step. The moldwas held until cooled below 200 F. The resultant molded panel measuredapproximately 12″×24″×¼″. The molded part exhibited the followingproperties: Tensile Tensile Flexural Strength (10³) Modulus (10⁶)Strength (10³) Axial 6.63 0.71 12.53 Direction Transverse 6.73 0.6711.56 Direction

[0154] Thus the molded panel exhibited mechanical properties in themachine and transverse directions within 20% of each other and aretherefore nearly anisotropic.

[0155] A burn off of the resin from the molded panel and analysis of theresidual glass fibers revealed that the average fiber length in themolded panel was 0.43″ versus the input length of 0.5″. This representsan 85% retention of the initial fiber length in the final moldedproduct.

EXAMPLE 2

[0156] A pre-compounded ABS (Acrylonitrile/Butadiene/Styrene) resincontaining 30% by weight of ½″ long glass fiber from LNP was extrudedaccording to Example 1 using the following extruder zone and dietemperatures: Zone 1@375 F; Zone 2@400 F; Zone 3@425 F; Zone 4@475 F;Zone 5@515 F; Zone 6@515; die temperature@515 F. Using the same mold asin Example 1, a sample panel of approximately 12″×24″×¼″ was preparedand exhibited the following properties: Tensile Modulus FlexuralStrength (10³) (10⁶) Strength (10³) Modulus (10⁶) Axial 7.02 0.95 12.960.71 Direction Transverse 7.53 0.77 10.96 0.60 Direction

[0157] The molded panel exhibits mechanical properties which are within20% of each other in the machine and transverse directions and thereforethe mechanical properties are nearly anisotropic.

[0158] A burn off of the resin from the molded panel and analysis of theresidual glass fibers revealed that the average fiber length in themolded panel was 0.30″ or 60% of the original fiber length.

EXAMPLE 3

[0159] A mixture of polypropylene and ½″ long fiberglass fibers (88%resin/12% glass fibers by weight) were processed in accordance withExample 1 using a wooden matched mold to produce a rigid, solid ribbedradome cover with dimensions of 12′ long×8′ wide×1″ thick and weighing120 pounds.

EXAMPLE 4

[0160] A mixture of polypropylene and ½″ long fiberglass fibers (70%resin/30% glass fibers by weight) were processed in accordance withExample 1 using a solid aluminum matched metal mold to produce a beam 7″high×4″ wide×8′ long with solid, diagonal reinforcing ribs and weighing22 pounds.

EXAMPLE 5

[0161] A mixture of Nylon 6 from General Polymers and ½″ long glassfibers (70% resin/30 glass fibers by weight) were processed according toExample 1 using extruder zone and die temperatures at least 100 C abovethe glass transition temperature of the resin to produce a 12″×24″×¼″panel.

EXAMPLE 6

[0162] A mixture of polyetheretherketone (PEEK) and 1″ long carbonfibers (70% resin/30% carbon fibers by weight) were processed accordingto Example 1 using extruder zone and die temperatures at least 100 Cabove the glass transition temperature of the resin to produce a12′×24″×¼″ panel.

EXAMPLE 7

[0163] A mixture of polyetheretherketone (PEEK) and ½″ Kevlar fibers(70% resin/30% Kevlar fibers by weight) were processed according toExample 1 using extruder zone and die temperatures at least 100 C abovethe glass transition temperature of the resin to produce a 12″×24″×¼″panel.

EXAMPLE 8

[0164] A mixture of polypropylene and 3″ long fiberglass fibers (80%resin/20% glass fibers by weight) were processed according to Example 1to produce a 12″×24″×¼″ panel.

EXAMPLE 9

[0165] A mixture of polypropylene and ½″ long fiberglass fibers (45%resin/55% glass fibers by weight) were processed according Example 1 toproduce a 12″×24″×¼″ panel.

EXAMPLE 10

[0166] A mixture of polypropylene and ½′ long fiberglass fibers (80%resin/20% glass fibers by weight) were processed according to Example 1to produce the two halves of a materials handling pallet which weresubsequently joined to produce a materials handling pallet withdimensions of 48″ long×40″ wide×6″ high and weighing 63 pounds.

EXAMPLE 11

[0167] A mixture of polypropylene and ½″ long fiberglass fibers (70%resin/30% glass fibers by weight) were processed according to Example 1to produce a supporting beam containing a 1″ square I.D. steel tubeinserted along its length and the beam had dimensions of 20′ long×12″high×6″ wide and weighed 180 pounds. The steel tube having been insertedinto the mold during the molten resin/glass mold filling step and beforethe final compression molding of the beam.

EXAMPLE 12

[0168] A mixture of polyethylene and 1″ long wood/cellulose dried fibers(80% resin/20% wood fibers) were processed according to Example 1 usingextruder zone and die temperatures at least 100° C. above the resinglass transition temperature to produce a 12″×24″×¼″ panel.

EXAMPLE 13

[0169] A mixture of SMA (Styrene/Maleic Anhydride) resin and ½″ longfiberglass fibers (82% resin/18% glass fibers by weight) were processedaccording to Example 1 using extruder zone and die temperatures at least100° C. above the glass transition temperature of the resin to produce a12″×24″×¼″ panel.

EXAMPLE 14

[0170] A mixture of PPS (polyphenylenesulfide) and ½″ long fiberglassfibers (70% resin/30% glass fibers by weight) were processed accordingto Example 1 using extruder zone and die temperatures at least 100 Cabove the glass transition temperature of the resin to produce a12″×24″×¼″ panel.

EXAMPLE 15

[0171] A mixture of PC (Polycarbonate) and ½″ long fiberglass fibers(80% resin/20% glass fibers by weight) were processed according toExample 1 using extruder zone and die temperatures at least 100 C abovethe glass transition temperature of the resin to produce a 12″×24″×¼″panel.

[0172] The molding process conducted in accordance with the presentinvention is conducted at substantially lower compression pressures thanthose typically used in the industry. Advantageously, these lowpressures permit the use of non-metallic molds, such as wooden molds,which would generally not be able to withstand the high pressures usedin the industry.

[0173] Any type of fibrous material can be used in the presentinvention. For example, the fibrous material can be glass fibers,fiberglass, carbon fibers, synthetic fibers, metal fibers, naturalfibers, cellulose, or wood.

[0174] Any kind of thermoplastic resin can be used to prepare articlesin accordance with the present invention. Examples of suitablethermoplastic resins are polyolefins, polyhaloolefins, polyaromatics,poly(alkenylaromatics), polystyrene, acrylonitrile/butadiene/styreneresins, polyamides, nylon, poly(carboxylic acids), polyamines,polyethers, polyacetals, polysulfones, poly(organicsulfides),poly(organicoxides), polyesters, polycarbonates, polyimides,polyurethanes, polyetheretherketone resins, styrene/maleic anhydrideresins, and mixtures thereof.

[0175] The thermoplastic resin can be a single polymer, or a mixture oftwo or more polymers. In particular embodiments, the thermoplastic resincan comprise a homopolymer, copolymer, random copolymer, alternatingcopolymer, block copolymer, graft copolymer, liquid crystal polymer, ora mixture of these polymers.

[0176] The thermoplastic resin can be a virgin resin, a recycled resin,or a mixture of a virgin resin and a recycled resin in any proportion.The thermoplastic resin may optionally comprise a coupling agent whichenhances bonding of the fibrous material to the resin.

[0177] Articles such as pallets, beams, doors, radomes, constructionproducts such as wall panels and modular components, pipes, pillars, andpiling can be successfully prepared according to the claimed invention.

[0178] The foregoing description is of a preferred embodiment forimplementing the invention, and the scope of the invention should not belimited by this description. The scope of the present invention isinstead defined by the following claims.

What is claimed is:
 1. A molded thermoplastic article comprising afibrous material embedded in a thermoplastic resin matrix, the articleprepared by a low shear process comprising the steps of: a) meltcompounding a mixture of a thermoplastic resin, the fibrous material,and any optional additives using a low shear single screw, wherein thelengths of the fibers of the fibrous material before molding are about0.5-3 inches long, and the fibrous material comprises 5-55% of the totalweight of the compounded mixture; b) extruding the mixture through asheet extrusion die using low shear extrusion; c) depositing theextruded mixture into a first half of a horizontally-movable matchedmold in approximately the general shape of the article; and d)compression molding the deposited mixture with the second half of thematched mold such that pressures in the range of 100-1,000 psi andsubstantially little movement of the molten mixture are required tocomplete consolidation and molding of the thermoplastic article,wherein: the lengths of the fibers of the fibrous material in the moldedarticle are greater than about 60% of their pre-molded lengths; lessthan about 20% of the fibers of the fibrous material in the moldedthermoplastic article are oriented in the same direction; and themechanical properties of the molded article in the x-, y-, and z-planesare within 20% of each other.
 2. The article according to claim 1,wherein the process is conducted substantially under low shearconditions.
 3. The article according to claim 1, wherein the extrusionis conducted through a multi-gated, horizontally mounted sheet extrusiondie with independently controlled gates capable of varying the thicknessof the mixture extruded through each gate.
 4. The article according toclaim 1, wherein the resin/fibrous material mixture is gravity-depositedin the mold in step c) in a molten net near shape laydown of the moldedarticle.
 5. The article according to claim 1, further comprisingtransferring the resin/fibrous material mixture through a transfer pipeprior to extrusion.
 6. The article according to claim 1, wherein thefibrous material is selected from the group consisting of glass fibers,fiberglass, carbon fibers, synthetic fibers, metal fibers, naturalfibers, cellulose, and wood.
 7. The article according to claim 1,wherein the thermoplastic resin is selected from the group consisting ofpolyolefins, polyhaloolefins, polyaromatics, poly(alkenylaromatics),polystyrene, acrylonitrile/butadiene/styrene resins, polyamides, nylon,poly(carboxylic acids), polyamines, polyethers, polyacetals,polysulfones, poly(organicsulfides), poly(organicoxides), polyesters,polycarbonates, polyimides, polyurethanes, polyetheretherketone resins,styrene/maleic anhydride resins, and mixtures thereof.
 8. The articleaccording to claim 1, wherein the thermoplastic resin is a homopolymer,copolymer, random copolymer, alternating copolymer, block copolymer,graft copolymer, liquid crystal polymer, or mixtures thereof.
 9. Thearticle according to claim 1, wherein the thermoplastic resin is avirgin resin, a recycled resin, or a mixture thereof.
 10. The articleaccording to claim 1, wherein the extrusion is conducted at atemperature in the range of 300-700° F.
 11. The article according toclaim 1, wherein the optional additive is a coupling agent whichenhances bonding of the fibrous material to the thermoplastic resin. 12.The article according to claim 1, wherein the mold is a metallic mold,non-metallic mold, ceramic mold, or a wooden mold.
 13. The articleaccording to claim 1, wherein the tensile strength, tensile modulus, andflexural strength of the article in the axial and transverse directionsare within 20% of each other.
 14. The article according to claim 1,wherein the lengths of the fibers of the fibrous material in the moldedarticle are greater than about 70% of their pre-molded lengths.
 15. Thearticle according to claim 1, wherein the lengths of the fibers of thefibrous material in the molded article are greater than about 80% oftheir pre-molded lengths.
 16. The article according to claim 1, whereinthe lengths of the fibers of the fibrous material in the molded articleare greater than about 90% of their pre-molded lengths.
 17. The articleaccording to claim 1, wherein the mechanical properties of the articleare substantially anisotropic.
 18. The article according to claim 1,wherein the length of the article in at least one of the z-, y-, andz-planes is greater than about 0.5 feet.
 19. The article according toclaim 1, wherein the length of the article in at least one of the z-,y-, and z-planes is greater than about 1.0 feet.
 20. The articleaccording to claim 1, wherein the length of the article in at least oneof the z-, y-, and z-planes is greater than about 2.0 feet.
 21. Thearticle according to claim 1, wherein the length of the article in atleast one of the z-, y-, and z-planes is greater than about 3.0 feet.22. The article according to claim 1, wherein the weight of the articleis greater than about 10 lbs.
 23. The article according to claim 1,wherein the weight of the article is greater than about 20 lbs.
 24. Thearticle according to claim 1, wherein the weight of the article isgreater than about 25 lbs.
 25. The article according to claim 1, whereinthe process is an insert molding process.
 26. A molded thermoplasticarticle comprising a fibrous material embedded in a thermoplastic resinmatrix, wherein: the lengths of the fibers of the fibrous materialbefore molding are about 0.5-3 inches long, and the fibrous materialcomprises 5-55% of the total weight of the compounded mixture; thelengths of the fibers of the fibrous material in the molded article aregreater than about 60% of their pre-molded lengths; less than about 20%of the fibers of the fibrous material in the molded thermoplasticarticle are oriented in the same direction; and the mechanicalproperties of the molded article in the x-, y-, and z-planes are within20% of each other.
 27. The article according to claim 26, wherein thefibrous material is selected from the group consisting of glass fibers,fiberglass, carbon fibers, synthetic fibers, metal fibers, naturalfibers, cellulose, and wood.
 28. The article according to claim 26,wherein the thermoplastic resin is selected from the group consisting ofpolyolefins, polyhaloolefins, polyaromatics, poly(alkenylaromatics),polystyrene, acrylonitrile/butadiene/styrene resins, polyamides, nylon,poly(carboxylic acids), polyamines, polyethers, polyacetals,polysulfones, poly(organicsulfides), poly(organicoxides), polyesters,polycarbonates, polyimides, polyurethanes, polyetheretherketone resins,styrene/maleic anhydride resins, and mixtures thereof.
 29. The articleaccording to claim 26, wherein the thermoplastic resin is a homopolymer,copolymer, random copolymer, alternating copolymer, block copolymer,graft copolymer, liquid crystal polymer, or mixtures thereof.
 30. Thearticle according to claim 26, wherein the thermoplastic resin is avirgin resin, a recycled resin, or a mixture thereof.
 31. The articleaccording to claim 26, wherein the resin comprises a coupling agentwhich enhances bonding of the fibrous material to the thermoplasticresin.
 32. The article according to claim 26, wherein the tensilestrength, tensile modulus, and flexural strength of the article in theaxial and transverse directions are within 20% of each other.
 33. Thearticle according to claim 26, wherein the lengths of the fibers of thefibrous material in the molded article are greater than about 70% oftheir pre-molded lengths.
 34. The article according to claim 26, whereinthe lengths of the fibers of the fibrous material in the molded articleare greater than about 80% of their pre-molded lengths.
 35. The articleaccording to claim 26, wherein the lengths of the fibers of the fibrousmaterial in the molded article are greater than about 90% of theirpre-molded lengths.
 36. The article according to claim 26, wherein themechanical properties of the article are substantially anisotropic. 37.The article according to claim 26, wherein the length of the article inat least one of the z-, y-, and z-planes is greater than about 0.5 feet.38. The article according to claim 26, wherein the length of the articlein at least one of the z-, y-, and z-planes is greater than about 1.0feet.
 39. The article according to claim 26, wherein the length of thearticle in at least one of the z-, y-, and z-planes is greater thanabout 2.0 feet.
 40. The article according to claim 26, wherein thelength of the article in at least one of the z-, y-, and z-planes isgreater than about 3.0 feet.
 41. The article according to claim 26,wherein the weight of the article is greater than about 10 lbs.
 42. Thearticle according to claim 26, wherein the weight of the article isgreater than about 20 lbs.
 43. The article according to claim 26,wherein the weight of the article is greater than about 25 lbs.
 44. Thearticle according to claim 26, further comprising one or more optionalreinforcing inserts.
 45. The article according to claim 44, wherein thereinforcing inserts are selected from the group consisting of tubes,rods, mesh, and combinations thereof.
 46. The article according to claim26, wherein the article has one or more solid raised three-dimensionalfeatures.
 47. The article according to claim 46, wherein the one or moresolid raised three-dimensional features are blind ribs, posts, mountingposts, or tabs.